Device for measuring metal linear expansion coefficient by using optical fiber displacement sensor

Abstract

The utility model discloses a device for measuring a metal linear expansion coefficient by using an optical fiber displacement sensor, relates to the technical field of metal linear expansion coefficient measuring equipment, and solves the problems that in the prior art, a metal bar to be measured is not positioned and supported in place, and experimental errors are easy to occur. The device comprises a base, a soaking pipe assembly is vertically arranged on the base, a plurality of elastic fixing pieces used for supporting a metal bar to be detected are fixedly arranged in the soaking pipe assembly, a support is arranged on the base, and an optical fiber displacement sensor used for being matched with the upper end of the metal bar to be detected is adjustably arranged on the support. According to the device, the plurality of elastic supporting pieces are arranged in the soaking pipe assembly, so that the metal piece to be tested placed in the soaking pipe assembly can be elastically supported, the centering and vertical states of the metal rod to be tested can be maintained, centering positioning and supporting are realized, and experimental errors are avoided or reduced.

Description

Technical Field

[0001] The utility model relates to the technical field of metal linear expansion coefficient measuring equipment, in particular to a device for measuring metal linear expansion coefficient by using an optical fiber displacement sensor. Background Art

[0002] The linear expansion coefficient is an important parameter that characterizes the expansion characteristics of materials. In particular, the measurement of the linear expansion coefficient of metals above room temperature is of great significance in actual engineering measurements. The measurement of the linear expansion coefficient of metals is a major content in ordinary physical experiments. The key to this experiment is how to accurately measure the small changes in the length of a metal rod caused by temperature changes. The methods for measuring small changes are usually the optical lever method and the micrometer screw method. The micrometer screw method has low accuracy and has a greater impact on the overall experimental data. Although the optical lever method can measure the small changes in the length of the metal rod very well, the optical lever method system is difficult to adjust and there are many physical quantities to be measured, so the experimental error introduced is large.

[0003] The Chinese utility model patent with publication number CN207636528U discloses a linear expansion coefficient detection device, including a heating furnace, a first clamp and a second clamp are provided at both ends of the heating furnace, the first clamp and the second clamp are respectively provided with a first clamping part and a second clamping part in the furnace cavity of the heating furnace for clamping the sample to be tested between the two clamps, and at least one of the first clamp and the second clamp is provided with a pressure sensor for detecting the pressure on the sample to be tested. The deformation of the sample to be tested is obtained by data processing based on the pressure difference before and after heating and the elastic modulus of the sample to be tested, thereby obtaining the linear expansion coefficient of the sample to be tested.

[0004] In the utility model, the positioning of the metal bar to be measured mainly relies on the first clamp and the second clamp to clamp the metal bar to be measured from both ends respectively, and the positioning member 7 at the bottom is used to position the lower end of the metal bar to be measured in the horizontal direction, but the upper end of the metal bar to be measured is not positioned. Due to the inadequate positioning and support of the metal bar to be measured, it is difficult to ensure the vertical state of the metal bar to be measured, causing the metal bar to be measured to tilt and fall, resulting in large measurement errors. The use of rigid support components such as guide blocks in other existing technologies also has gap installation errors, making it difficult to ensure the centering and verticality of the metal bar to be measured. Utility Model Content

[0005] In view of the deficiencies in the above-mentioned background technology, the utility model proposes a device for measuring the linear expansion coefficient of metal using an optical fiber displacement sensor, which solves the problem in the prior art that the metal rod to be measured is not properly positioned and supported, which easily leads to experimental errors.

[0006] The technical solution of the utility model is implemented as follows: a device for measuring the linear expansion coefficient of metal using an optical fiber displacement sensor, comprising a base, a heat spreader assembly is vertically arranged on the base, a plurality of elastic fixings for supporting a metal rod to be measured are fixedly arranged in the heat spreader assembly, a bracket is arranged on the base, and an optical fiber displacement sensor for cooperating with the upper end of the metal rod to be measured is adjustably arranged on the bracket.

[0007] Preferably, the elastic fixing member comprises a clamping ring fixedly mounted on the heat absorbing tube assembly, the clamping ring is connected to a support sheet, a circular hole is provided on the support sheet, and a plurality of elastic support sheets are provided at equal intervals in the circular hole. Further, the support sheet and the elastic support sheet are integrally formed.

[0008] Preferably, the heat-balancing pipe assembly includes a bottom insulation plate fixed on a base, the bottom insulation plate is connected to the lower end of the heat-conducting pipe, a plurality of clamping rings are coaxially arranged and fixed on the inner wall of the heat-conducting pipe at equal vertical intervals by bolts, the heat-conducting pipe is connected to the heating unit, and the upper end of the heat-conducting pipe is plugged into and fitted with the upper cover.

[0009] Preferably, the heating unit comprises a heating belt wound around the heat conducting pipe, and the outer wall of the heat conducting pipe is fixedly connected to the base via a support rod.

[0010] Furthermore, a heat preservation and heat insulation layer covering the heat conduction pipe and the heating belt is arranged outside the heat conduction pipe. A through hole coaxially arranged with the clamping ring is arranged in the middle of the upper cover, and a heat insulation rod is slidably arranged in the through hole.

[0011] Preferably, the base includes a bottom plate, the bottom heat insulation plate is bolted to the bottom plate, a support platform is provided on one side of the bottom plate, and a support rod is connected to a side wall of the support platform.

[0012] Preferably, the bracket includes a column vertically fixed on a support platform, a cantilever is rotatably provided on the column, and the cantilever can slide vertically along the column, a clamp seat is provided at the end of the cantilever, the optical fiber displacement sensor is detachably arranged on the clamp seat, and a fastening handle cooperating with the column is provided on the cantilever.

[0013] Preferably, a controller is provided on the support platform, the controller is electrically connected to the optical fiber displacement sensor, the controller is electrically connected to the temperature sensor, the temperature sensor is pasted and fixed to the outer wall of the metal rod to be tested, and the upper cover is provided with a through hole for the temperature sensor to penetrate.

[0014] The beneficial effects of the utility model are as follows: by setting up a heat-saturating tube assembly, the metal rod to be tested can be heated and the temperature can be maintained. By adjusting the optical fiber displacement sensor on the bracket, the position of the optical fiber displacement sensor and the distance from the end of the metal rod to be tested can be adjusted, and the installation and removal of the metal rod to be tested can be facilitated. By setting up a plurality of elastic support members in the heat-saturating tube assembly, the metal member to be tested placed therein can be elastically supported, the centering and vertical state of the metal rod to be tested can be maintained, and the centering positioning and support can be achieved, thereby avoiding or reducing experimental errors. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present utility model, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0016] Figure 1 This is a schematic diagram of the external three-dimensional structure of the utility model;

[0017] Figure 2 This is a schematic diagram of the cross-sectional structure of the utility model;

[0018] Figure 3 This is a schematic diagram of the structure of the elastic fixing member of the utility model;

[0019] Figure 4 This is a schematic diagram of the support structure of the utility model;

[0020] Figure 5 This is a schematic diagram of the installation completion status of the metal rod to be tested in the utility model;

[0021] Figure 6 This is a schematic diagram of the matching state between the metal rod to be tested and the elastic fixing piece of the utility model;

[0022] In the figure: 1: base, 2: heat-averaging tube assembly, 3: metal rod to be tested, 4: elastic fixing part, 5: bracket, 6: optical fiber displacement sensor, 7: clamping ring, 8: support plate, 9: elastic support plate, 10: bottom insulation plate, 11: heat conducting tube, 12: heating unit, 13: upper cover, 14: support rod, 15: insulation rod, 16: bottom plate, 17: support table, 18: column, 19: cantilever, 20: clamp seat, 21: temperature sensor, 22: fastening handle. DETAILED DESCRIPTION

[0023] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0024] like Figure 1 , 5 As shown, in Example 1, a device for measuring the linear expansion coefficient of metal using an optical fiber displacement sensor comprises a base 1, which provides a mounting support foundation for the other components. A heat spreader assembly 2 is vertically arranged on the base 1, and a plurality of elastic fixing members 4 for supporting a metal rod 3 to be measured are fixedly arranged inside the heat spreader assembly 2. The heat spreader assembly can heat and maintain the temperature of the metal rod to be measured. A bracket 5 is arranged on the base 1, and an optical fiber displacement sensor 6 for cooperating with the upper end of the metal rod 3 to be measured can be adjusted on the bracket 5. In this embodiment, by adjusting the optical fiber displacement sensor on the bracket, it is convenient to adjust the position of the optical fiber displacement sensor and the distance from the end of the metal rod to be measured, and it is also convenient to install and remove the metal rod to be measured.

[0025] When this embodiment is used, the optical fiber displacement sensor 6 is adjusted to one side through the bracket, and then the metal rod to be tested is installed into the heat-scaling tube assembly, and the metal rod to be tested is centered and supported by the elastic fixing member 4, and the optical fiber displacement sensor 6 is aligned with the end of the metal rod to be tested, and the metal rod to be tested is heated by the heat-scaling tube assembly. During the temperature change, the optical fiber displacement sensor 6 is used to measure the length change of the metal rod to be tested, so as to calculate the metal linear expansion coefficient of the metal rod to be tested. This embodiment provides a plurality of elastic support members, so that the metal member to be tested placed therein can be elastically supported, and the centering and vertical state of the metal rod to be tested can be maintained, so as to achieve centering positioning and support, thereby avoiding or reducing experimental errors.

[0026] Embodiment 2, on the basis of embodiment 1, as Figure 2As shown, the heat-equalizing pipe assembly 2 includes a bottom heat-insulating plate 10 fixed on the base 1. The heat-insulating plate is made of conventional heat-insulating materials such as marble to achieve better heat-insulating effect, avoid or reduce heat transfer causing the base and other components to be deformed by heat, affecting the measurement results. The bottom heat-insulating plate 10 is connected to the lower end of the heat-conducting pipe 11, and the bottom heat-insulating plate and the heat-conducting pipe can be plugged or connected by bolts. Several elastic fixings 4 are coaxially arranged and fixed on the inner wall of the heat-conducting pipe 11 at equal intervals vertically by bolts. When installing the metal rod to be tested, the metal rod to be tested is inserted into several elastic fixings one after another, and the elastic fixings work together to support and limit the metal rod to be tested in the middle, and at the same time, the lower end of the metal rod to be tested abuts against the middle of the bottom heat-insulating plate. The heat-conducting pipe 11 is connected to the heating unit 12. In this embodiment, the heating unit 12 includes a heating belt wound around the heat-conducting pipe 11, and the heating belt can heat the heat-conducting pipe, and then the metal rod to be tested inside is evenly heated through air heat transfer. In this embodiment, the heating belt is electrically connected to the auto-coupling voltage regulator, and the auto-coupling voltage regulator controls the voltage change and thus controls the heating power of the heating belt.

[0027] In addition, the upper end of the heat pipe 11 is plugged into the upper cover 13, so that the upper cover can be quickly removed when installing or removing the metal rod to be tested. A through hole is provided in the middle of the upper cover 13 coaxially with the elastic fixing member 4, and a heat insulating rod 15 is slidably provided in the through hole. The heat insulating rod can not only close the through hole in the middle of the upper cover to play a heat insulating role, but also make the lower end contact with the end of the metal rod to be tested. When the length of the metal rod to be tested changes due to heating, the heat insulating rod is driven to slide synchronously upward, and then the optical fiber displacement sensor 6 is used to measure the length change of the metal rod to be tested, and the synchronous sliding of the heat insulating rod 15 plays a role in transmitting displacement.

[0028] As a further embodiment, the heat pipe 11 is provided with a heat preservation and heat insulation layer covering the heat pipe 11 and the heating belt. The heat preservation layer uses conventional heat insulation materials to reduce heat loss and the influence of heat on other components. As a further optional embodiment, in order to better support the heat pipe, the outer wall of the heat pipe 11 is fixedly connected to the base 1 through a support rod 14. In this embodiment, when a heat preservation and heat insulation layer is provided, the support rod 14 is fixedly connected to the base, and a clamp is provided outside the heat preservation and heat insulation layer. The support rod is fixedly connected to the clamp to further fix the heat pipe.

[0029] Embodiment 3, on the basis of embodiment 1, as Figure 3 As shown, the elastic fixing member 4 includes a clamping ring 7 fixed on the heat absorbing tube assembly 2, the clamping ring 7 is connected to a support sheet 8, a circular hole is provided on the support sheet 8, and a plurality of elastic support sheets 9 are provided at equal intervals in the circumferential direction of the circular hole. In this embodiment, the support sheet 8 and the elastic support sheet 9 are integrally formed.

[0030] In this embodiment, the clamping ring 7 is riveted to the support sheet 8, and the elastic support sheet 9 and the support sheet can be made of conventional heat-resistant rubber or a metal sheet with good elasticity. Figure 5 , 6 As shown in the figure, when the metal rod to be tested is inserted, the elastic support sheet is simultaneously driven to bend downward, and the end of the elastic support sheet contacts the side wall of the metal rod to be tested. Under the joint action of the elastic support sheets arranged circumferentially at equal intervals, the metal rod to be tested is maintained in the middle and in a vertical posture. The elastic support sheet and the metal rod to be tested are in a sliding fit. When the metal rod to be tested expands due to heat, the two can slide relative to each other along the length direction.

[0031] Embodiment 4, on the basis of embodiment 3, as Figure 4 , 6 As shown, the base 1 includes a bottom plate 16, a bottom heat insulation plate 10 is bolted to the bottom plate 16, a support platform 17 is provided on one side of the bottom plate 16, and a support rod 14 is fixedly connected to the side wall of the support platform 17, so that the support platform is used to support the heat pipe.

[0032] The bracket 5 includes a vertical column 18 whose lower end is fixed on a support platform 17. A cantilever 19 is rotatably provided on the column 18. The cantilever 19 can slide vertically along the column 18. In this embodiment, a circular hole is provided at one end of the cantilever, and the column is inserted into the circular hole. A fastening handle 22 cooperating with the column 18 is threaded on the cantilever 19. When the cantilever position needs to be locked, the fastening handle is rotated so that its end abuts against the side wall of the column to form a lock. When the cantilever needs to be moved, the fastening handle is rotated to release the lock on the position of the cantilever and the column. A clamp seat 20 is provided at the other end of the cantilever 19, and the optical fiber displacement sensor 6 is detachably arranged on the clamp seat 20. In this embodiment, the clamping seat includes a fixed seat arranged at the end of the cantilever and a movable seat connected to the fixed seat by bolts. A groove for setting the optical fiber displacement sensor 6 is correspondingly provided between the movable seat and the fixed seat. The measuring head on the side of the optical fiber displacement sensor 6 is coaxially arranged with the metal rod 3 to be measured, the heat conducting tube 11, the insulation rod 15, and the elastic fixing member 4, so that the optical fiber displacement sensor 6 can cooperate with the end of the insulation rod 15 to realize the monitoring of the displacement.

[0033] A controller is provided on the support platform 17, and the controller can be a single chip microcomputer. The controller is electrically connected to the optical fiber displacement sensor 6, and the controller is electrically connected to the temperature sensor 21. The temperature sensor 21 is fixed to the outer wall of the metal rod 3 to be tested, and a through hole is provided on the upper cover 13 to allow the temperature sensor to penetrate, so that the temperature of the metal rod to be tested can be monitored and fed back in real time. During measurement, the controller can collect data output by the temperature sensor and the optical fiber displacement sensor in real time, and calculate the linear expansion coefficient of the metal rod based on the collected data.

[0034] Embodiment 5, based on the above embodiment, after the metal rod to be measured is installed, the measurement includes the following steps:

[0035] First, calibration measurement is performed to maintain a constant temperature. The distance between the measuring head of the optical fiber displacement sensor 6 and the upper end of the insulation rod is gradually changed. The distance x is measured and recorded using existing measuring tools such as a micrometer or a vernier caliper. At the same time, the output voltage value u of the corresponding optical fiber displacement sensor 6 is recorded to obtain the ux relationship curve, find the approximate linear part of the ux relationship curve, and then calculate the fitting slope k1 of the curve.

[0036] Then, the metal rod to be tested is heated by a heating belt, and the temperature reading t of the temperature sensor and the output voltage value u of the optical fiber displacement sensor 6 are recorded in real time. The corresponding relationship between u and t is fitted to obtain the ut fitting curve of the metal rod to be tested, and then the fitting slope k2 of the curve is calculated.

[0037] Equivalent fitting slope of xt curve

[0038] Expansion coefficient formula for metal rod Among them, l0 is the original length of the metal rod to be measured, Δt=t2-t1 is the temperature change, and Δl=l2-l1 is the corresponding elongation. The distance change Δx of the measuring head of the optical fiber displacement sensor 6 relative to the upper end of the insulation rod can be converted into the displacement change Δl=-Δx caused by the heating and expansion of the metal rod. The expansion coefficient of the metal rod is calculated by the formula

[0039]

[0040] The measuring device is based on the optical fiber displacement sensor 6. The observation of small displacement and temperature is more convenient and intuitive than traditional experiments, and the readings are real-time and accurate. The disassembly and assembly of the experimental instrument is more convenient, the experimental operation steps are simplified, the experimental error is extremely small, and the overall cost performance is high. The optical fiber displacement sensor is transferred from the industrial processing field to the laboratory, which provides a new method for measuring the linear expansion coefficient of metals, and can replace traditional experiments and be used for experimental teaching. The above is only a preferred embodiment of the utility model, and is not intended to limit the utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the utility model should be included in the protection scope of the utility model.

Claims

1. A device for measuring the linear expansion coefficient of a metal using an optical fiber displacement sensor, comprising a base (1), characterized in that: A heat-scaling tube assembly (2) is vertically arranged on the base (1), a plurality of elastic fixing members (4) for supporting a metal rod (3) to be measured are fixedly arranged inside the heat-scaling tube assembly (2), a bracket (5) is arranged on the base (1), and an optical fiber displacement sensor (6) for cooperating with the upper end of the metal rod (3) to be measured is adjustably arranged on the bracket (5).

2. The device for measuring the linear expansion coefficient of metal using an optical fiber displacement sensor according to claim 1, characterized in that: The elastic fixing member (4) comprises a clamping ring (7) fixedly mounted on the heat equalizing tube assembly (2), the clamping ring (7) being connected to a support sheet (8), a circular hole being provided on the support sheet (8), and a plurality of elastic support sheets (9) being provided at equal intervals in the circumferential direction of the circular hole.

3. The device for measuring the linear expansion coefficient of metal using an optical fiber displacement sensor according to claim 2, characterized in that: The support sheet (8) and the elastic support sheet (9) are integrally formed.

4. The device for measuring the linear expansion coefficient of metal using an optical fiber displacement sensor according to claim 2 or 3, characterized in that: The heat-equalizing pipe assembly (2) comprises a bottom heat-insulating plate (10) fixed on a base (1), the bottom heat-insulating plate (10) being connected to the lower end of a heat-conducting pipe (11), a plurality of clamping rings (7) being coaxially arranged and fixed to the inner wall of the heat-conducting pipe (11) at equal intervals vertically by bolts, the heat-conducting pipe (11) being connected to a heating unit (12), and the upper end of the heat-conducting pipe (11) being plugged into and fitted with an upper cover (13).

5. The device for measuring the linear expansion coefficient of metal using an optical fiber displacement sensor according to claim 4, characterized in that: The heating unit (12) comprises a heating belt wound around the heat conducting tube (11), and the outer wall of the heat conducting tube (11) is fixedly connected to the base (1) via a support rod (14).

6. The device for measuring the linear expansion coefficient of metal using an optical fiber displacement sensor according to claim 5, characterized in that: The heat conducting pipe (11) is provided with a heat preservation and heat insulating layer covering the heat conducting pipe (11) and the heating belt.

7. The device for measuring the linear expansion coefficient of metal using an optical fiber displacement sensor according to claim 6, characterized in that: A through hole coaxially arranged with the clamping ring (7) is provided in the middle of the upper cover (13), and a heat insulating rod (15) is slidably arranged in the through hole.

8. The device for measuring the linear expansion coefficient of metal using an optical fiber displacement sensor according to any one of claims 5 to 7, characterized in that: The base (1) comprises a bottom plate (16), a bottom heat insulation plate (10) is bolted to the bottom plate (16), a support platform (17) is provided on one side of the bottom plate (16), and a support rod (14) is connected to a side wall of the support platform (17).

9. The device for measuring the linear expansion coefficient of metal using an optical fiber displacement sensor according to claim 8, characterized in that: The bracket (5) comprises a column (18) vertically fixed on a support platform (17); a cantilever (19) is rotatably provided on the column (18), and the cantilever (19) can slide vertically along the column (18); a clamping seat (20) is provided at the end of the cantilever (19); the optical fiber displacement sensor (6) is detachably provided on the clamping seat (20); and a fastening handle (22) is provided on the cantilever (19) that cooperates with the column (18).

10. The device for measuring the linear expansion coefficient of metal using an optical fiber displacement sensor according to claim 9, characterized in that: The support platform (17) is provided with a controller, the controller is electrically connected to the optical fiber displacement sensor (6), the controller is electrically connected to the temperature sensor (21), the temperature sensor (21) is glued and fixed to the outer wall of the metal rod (3) to be tested, and the upper cover (13) is provided with a through hole for the temperature sensor (21) to penetrate.

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