CN212207178U - Measuring device and system for linear expansion coefficient of metal - Google Patents
Measuring device and system for linear expansion coefficient of metal Download PDFInfo
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- CN212207178U CN212207178U CN202020626127.5U CN202020626127U CN212207178U CN 212207178 U CN212207178 U CN 212207178U CN 202020626127 U CN202020626127 U CN 202020626127U CN 212207178 U CN212207178 U CN 212207178U
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Abstract
The utility model discloses a measuring device and system of coefficient of linear expansion of metal, this measuring device includes: the soaking structure is composed of a quartz tube, a heating belt and a heat insulation layer, wherein the heating belt is wound on the outer side of the quartz tube, and a metal rod is heated in a mode of being placed in the quartz tube and is supported in the quartz tube in a suspended mode; the first grating displacement sensor consists of a movable end and a fixed end of a grating ruler, is positioned at one axial end of the metal rod to be measured, and is abutted by a first spring and the first fixed end to measure the expansion displacement of the first spring; and a thermocouple temperature sensor, wherein a thermocouple probe of the thermocouple temperature sensor is adhered to the metal rod by a heat-resistant adhesive tape and is used for measuring the temperature of the metal rod in real time, and heat insulation pieces are arranged at two axial end parts of the metal rod to be measured. The measuring device provides a new way for measuring the linear expansion coefficient, and can replace the traditional experiment and be used for experimental teaching.
Description
Technical Field
The utility model relates to a measuring device of coefficient of metal linear expansion and measuring system of coefficient of metal linear expansion.
Background
The linear expansion coefficient is an important parameter for representing the expansion characteristic of a substance, and is particularly significant in actual engineering measurement for the measurement of the linear expansion coefficient of metal above normal temperature.
Methods for measuring minute variations are often optical lever methods and spirometry. And the screw micrometer is used, so that the precision is low, and the influence on the whole experimental data is large.
The method for measuring the linear expansion coefficient of metal mainly comprises the steps of converting a tiny length variation into a tiny angle variation through an optical lever device, converting the tiny angle variation into a larger reading variation on a graduated scale through a scale telescope, and calculating to obtain the tiny variation.
The difficulty is great to utilize the optical lever principle to adjust, and the optical lever mirror surface can not strictly be perpendicular with the optical axis of telescope, often the optical lever level crossing can have certain angle with the telescope, causes the scale reading in the telescope to have the deviation, observes displacement volume magnification through the telescope and is too big, can make the result receive the influence, and the measuring volume is very much, measures the deviation great to the value of the small displacement volume that makes the experiment measure is not accurate enough.
Therefore, it is necessary to provide a measuring device for measuring the linear expansion coefficient of a metal with accuracy and convenience in operation.
SUMMERY OF THE UTILITY MODEL
An object of the utility model is to provide a measuring device of coefficient of linear expansion to make the measurement of linear expansion accurate and easy and simple to handle.
An object of the utility model is also to provide a measurement system of coefficient of linear expansion carries out automatic measure to the coefficient of linear expansion.
Therefore, the utility model discloses an aspect provides a measuring device of coefficient of linear expansion of metal, include: the soaking structure is composed of a quartz tube, a heating belt and a heat insulation layer, wherein the heating belt is wound on the outer side of the quartz tube, and a metal rod to be measured is heated in a mode of being placed in the quartz tube and is supported in the quartz tube in a suspended mode; a thermocouple temperature sensor, wherein a thermocouple probe of the thermocouple temperature sensor is stuck with the metal bar by a heat-resistant adhesive tape and is used for measuring the temperature of the metal bar in real time; and the first grating displacement sensor is composed of a movable end and a fixed end of a grating ruler, is positioned at one axial end of the metal rod to be measured and is used for measuring the expansion displacement of the metal rod to be measured, wherein heat insulation pieces are arranged at two axial ends of the metal rod to be measured, and the movable end of the grating ruler is in gapless contact with one axial end of the metal rod to be measured.
Furthermore, the device for measuring the linear expansion coefficient of the metal further comprises a second grating displacement sensor which is composed of a moving end and a fixed end of a grating ruler and is used for differentially measuring the expansion displacement of the metal rod, wherein the other axial end of the metal rod to be measured is in gapless contact with the moving end of the grating ruler of the second grating displacement sensor.
Furthermore, the device for measuring the linear expansion coefficient of the metal also comprises a spring with adjustable pressure, which is abutted against the moving end of the grating ruler.
Furthermore, one axial end of the metal rod to be measured is a fixed end, and the other axial end is a free telescopic end which is abutted to the moving end of the grating ruler.
Further, the device for measuring the linear expansion coefficient of the metal further comprises a linear slide rail, a first slide block and a second slide block, wherein the soaking structure is arranged on the linear slide rail, and parts located at two axial ends of the soaking structure are respectively arranged on the first slide block and the second slide block.
Furthermore, the device for measuring the linear expansion coefficient of the metal also comprises a grating ruler number display meter electrically connected with the grating displacement sensor, a thermocouple probe electrically connected with a display of the thermocouple temperature sensor, and a contact type self-coupling voltage regulator electrically connected with the heating belt.
According to another aspect of the present invention, there is provided a measuring system of linear expansion coefficient of metal, comprising a measuring device, a data processing device and a display device, wherein the measuring device is a measuring device of linear expansion coefficient of metal according to the above description.
The temperature measuring device adopts the scheme that the grating displacement sensor is used for measuring the linear expansion coefficient of metal: the high-precision grating displacement sensor is adopted to measure the tiny change quantity of the metal expansion, and then the linear expansion coefficient of the metal is calculated according to the real-time temperature recorded by the thermocouple temperature sensor.
Compared with the traditional optical lever method, the measuring device has the following technical effects aiming at the aspects of experimental instruments, operation steps and the like:
(1) in the measuring device, devices such as a quartz tube, a heat-preservation heat-insulation sponge, a heat-insulation piece and the like are designed, so that errors caused by thermal expansion of other structures of instruments such as a grating displacement sensor and the like are effectively prevented.
(2) Sleeving a metal rod in the center of the quartz tube, heating the quartz tube by a heating belt, and then uniformly heating the metal rod by air heat transfer; the voltage change is controlled by the autotransformer to further control the power of the heating belt, and the temperature of the metal rod is slowly increased under the heating of the heating belt.
(3) The temperature measuring device can obtain the linear expansion coefficient of the measured metal by fitting an x-t curve and according to an equivalent formula of the linear expansion coefficient of the metal, relevant documents indicate that the linear expansion coefficient of the metal is not a simple linear relation, and the measurement method can be used for well verifying the point.
In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be described in further detail with reference to the drawings.
Drawings
The accompanying drawings, which form a part of the present application, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:
fig. 1 is a schematic structural view of a device for measuring a linear expansion coefficient of a metal according to a first embodiment of the present invention;
fig. 2 is a schematic cross-sectional view of a device for measuring the coefficient of linear expansion of a metal according to a first embodiment of the present invention;
fig. 3 is a schematic structural diagram of a device for measuring the linear expansion coefficient of a metal according to a second embodiment of the present invention;
FIG. 4 is a graph of an x-t fit of an aluminum bar experimentally obtained with a measuring device according to the present invention; and
fig. 5 is a block diagram of a device for measuring the coefficient of linear expansion of a metal according to the present invention.
Detailed Description
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.
Fig. 1 to 5 show some embodiments according to the invention.
Fig. 1 and 2 show a first embodiment according to the present invention, and with reference to fig. 1 and 2, in this embodiment, the device for measuring the linear expansion coefficient of the metal comprises: the device comprises a quartz tube 11, a heating belt 12, a sponge heat insulation layer 13, a second end heat insulation piece 14, a second fixed end 15, a contact type self-coupling voltage regulator 16, a thermocouple probe 17, a thermocouple temperature sensor 18, a first grating displacement sensor consisting of a grating ruler moving end 21 and a fixed end 22, a first spring 23, a first fixed end 24, a first end heat insulation piece 25 and a first grating ruler digital display meter 26.
In the present embodiment, the grating displacement sensor is selected from a KA-300 grating ruler with an accuracy of 5 μm. The digital display meter of the grating ruler is preferably a GS898-2 digital display meter, is matched with the grating displacement sensor and is used for displaying the displacement of the grating ruler.
The contact type autotransformer is selected from TGC contact type autotransformers and is used for adjusting power voltage to be used as a heating belt power supply. The thermocouple temperature sensor is selected from a TM-902C thermometer and is used for measuring the real-time temperature of the metal rod. The first and second insulation members are selected from asbestos insulation panels.
Due to the large heat conduction coefficient of the metal bar, the temperature rises quickly, and if the heating belt (with the power of 100w) is directly wound outside the metal bar, the temperature rising speed is too fast, for example, the temperature of the aluminum bar rises by 1-2 degrees every second, so that the data recording is inconvenient, and the measurement error is too large.
In order to prevent uneven heating caused by direct contact between the metal rod and the quartz tube, two heat insulation clamping grooves 19 are designed at two ends of the quartz tube for supporting the metal rod in a suspended manner (as shown in fig. 2), so that the metal rod 40 is positioned at the center of the quartz tube and is not in contact with the quartz tube.
So make the heating band heat the quartz capsule earlier, then pass through the intraductal air heat transfer of quartz and make the metal rod heat up, this kind of heating methods makes the metal rod be heated evenly.
In order to ensure that the temperature of metal can be uniformly changed at a moderate speed, an auto-coupling voltage regulator is connected into a circuit, and the voltage change is controlled through an adjustable auto-coupling voltage regulator, so that the power of a heating belt is controlled, and the temperature rise of a metal rod is slow and adjustable. In order to ensure the accuracy of measurement, the temperature rise speed is not easy to be too fast, and is generally 1-2 ℃ per minute (the voltage of the self-coupling voltage regulator is about 60V at the moment).
The heat insulation pieces such as the asbestos plates are respectively arranged at the two ends of the metal rod, and the layer of heat insulation sponge is surrounded outside the heating device, so that the heat insulation and heat insulation purposes of the whole experimental device are achieved, and the errors caused by expansion of other structures due to the fact that the metal rod is in contact with other structures (such as a grating ruler) and the heat dissipation of the heating device are reduced.
The thermocouple probe is adhered to the metal rod with heat resisting adhesive tape, and the temperature of the metal rod is measured timely and displayed directly on the temperature sensor. The advantage is that the real-time temperature of the metal bar can be directly read without reading the reading number of the traditional thermometer, and the experiment becomes simpler, more convenient and more intuitive.
The metal bar is heated to expand to push the asbestos plate, the asbestos plate further pushes the movable end of the movable grating ruler to realize that the movable end of the grating ruler is in gapless contact with one axial end part of the metal bar, the movable end of the grating ruler slides for a small distance under the driving of the sliding rail, and the grating ruler digital display meter displays the moving distance of the grating ruler.
In order to reduce the overlong preheating time (the time from the beginning of heating to the beginning of changing the digital display representation number) caused by the existence of a gap in the device, a spring is added at the rightmost end of the experimental device for pressurization, and the elastic force generated by the elastic deformation of the spring does not influence the displacement size generated by the thermal expansion of the metal rod. Meanwhile, in order to further avoid idle stroke errors of the device, the first measurement data obtained after temperature rise is abandoned, and data after the second group is taken as effective experimental data.
The measuring object of the measuring device is a metal rod such as an aluminum rod, a copper rod, an iron rod, a silver rod, a gold rod and the like.
The method of measuring the linear expansion coefficient by using the apparatus will be described below by taking an aluminum rod having a length of 30cm and a purity of 99.99% as an example.
A) Record Room temperature T0。
B) Installing an aluminum bar: the temperature sensor probe is connected with the aluminum bar through an adhesive tape, the aluminum bar is placed in clamping grooves at two ends in the quartz tube, the first asbestos plate and the second asbestos plate are placed at two ends of the aluminum bar, and the whole device is located on the same straight line. Preferably, the soaking structure composed of a quartz tube and the like is fixedly arranged on the linear slide rail, parts at two ends of the soaking structure are respectively arranged on the two sliding blocks, and the final positions of the two sliding blocks are fixed by screws, so that the whole device is ensured to be on a straight line and the installation and operation of the aluminum bar are convenient.
C) And switching on a power supply, adjusting the zero digital display meter, adjusting the initial voltage of the autotransformer by about 50V, starting an experiment, and recording data. And recording the temperature sensor reading t and the digital display reading x once when the digital display reading of the grating ruler is increased by 5 micrometers, and slowly adjusting the voltage of the autotransformer to be between 50V and 60V.
D) The test data is recorded as follows:
TABLE 1 recording of Experimental data
E) The corresponding relation of the temperature sensor index t and the number display index x is obtained, and an x-t fitting curve of the aluminum bar can be obtained by fitting through software by a computer, as shown in fig. 4.
Observing the x-t curve can obtain: within a certain temperature range, the small variation of the linear expansion length of the aluminum bar is in direct proportion to the variation of the temperature. From the x-t curve fitted by the experimental data, the fitting slope k of the curve is 7.0021.
Equivalent formula calculated by substituting slope k into aluminum bar expansion coefficient
The linear expansion coefficient of the aluminum bar was found to be 23.34 × 10-6(℃-1)。
Theoretical value alpha of linear expansion coefficient of metallic aluminum0＝23.2×10-6(℃-1) To obtain
Δα＝|α0-α|＝0.14×10-6(℃-1)
Therefore, it is
Therefore, the experimental error is very small, the relative error is only 0.60%, and the requirement of the experiment is met.
Compared with the original experiment, the experiment has relatively low cost, and the cost is only hundreds of yuan; the experimental instrument is more convenient to disassemble and assemble; the experiment process is simple and direct and can be generally and smoothly carried out; compared with the traditional experiment, the observation of the displacement tiny amount and the temperature is more convenient and visual, and the reading is real-time and accurate; the operation steps are simplified, the experimental error is extremely small, and the comprehensive cost performance is higher.
The measuring device transfers the grating displacement sensor from the industrial processing field to a laboratory, provides a new method for measuring the linear expansion coefficient of metal, and can replace the traditional experiment and be used for experimental teaching. In addition, the purity of the metal material can be checked by comparing the experimental value of the linear expansion coefficient with the theoretical value by using the experiment.
Fig. 3 shows according to the second embodiment of the present invention, as shown in fig. 3, the measuring device of the linear expansion coefficient of metal of this embodiment includes a second grating displacement sensor (composed of a grating ruler moving end 31 and a fixed end 32), a second spring 33 and a second grating ruler digital display table 36, which are symmetrically disposed at the other end of the metal rod to be measured.
In the embodiment, the metal rod to be measured is arranged between the first grating displacement sensor and the second grating displacement sensor in a follow-up manner, so that both ends of the metal rod to be measured are allowed to extend freely, the expansion displacement of the metal rod can be measured differentially, the effect of measuring the expansion displacement of the metal rod is very ideal, the obstruction of the expansion of the metal rod caused by a fixed-end and free-end stretching mode can be overcome, and the measurement of the expansion displacement is more accurate and reliable.
Preferably, the first and second fixed ends 24 and 15 are adjustable fixed ends for adjusting the spring pressure.
In one embodiment, the first and second thermal insulation members are thermal insulation caps that are placed over the metal bar so that the metal bar is more easily and quickly installed.
Fig. 5 is a block diagram of a measuring system of linear expansion coefficient of metal according to the present invention, and as shown in fig. 5, the measuring system includes a measuring device 100, a data processing device 200, and a display device 300. Wherein, measuring device 100 is used for surveying the real-time temperature of metal bar and the extension displacement volume of metal bar, and data processing unit 200 is used for calculating the linear expansion coefficient and is used for controlling the voltage pressure regulating speed of heating tape according to the real-time temperature and the real-time displacement volume of gathering, and display device 300 is used for outputting data, x-t curve chart and the linear expansion coefficient of data processing unit 200, so the experimenter only need with the metal bar that awaits measuring and temperature measuring device 100 equipment can, realize automatic measurement metal wire expansion system next.
In the embodiment shown in fig. 1 and 3, the measurement device is configured for manual experimentation, requiring manual processing of the data. However, as a measuring device of the measuring system, some adjustment needs to be made in the structure.
The measuring device of the measuring system comprises a soaking structure consisting of a quartz tube 11, a heating belt 12 and a sponge heat-insulating layer 13, a thermocouple temperature sensor 17 for measuring the temperature of the metal rod in real time, one or two grating displacement sensors for measuring the expansion displacement of the metal rod in real time, and heat insulating pieces arranged at the two axial end parts of the metal rod to be measured. Wherein, the display of the thermocouple temperature sensor and the grating ruler digital display meter can be replaced by the display device 300. The contact autotransformer is replaced by an automatic voltage regulator or an automatic voltage regulation function module of the data processing device 200.
The method for calculating the linear expansion coefficient by the data processing device 200 according to the acquired real-time temperature and the real-time displacement is as follows: acquiring data of a temperature sensor and a grating displacement sensor in real time, obtaining an x-t fitting curve of the metal rod through fitting according to the corresponding relation of the reading t of the temperature sensor and the display reading x of the digital display, calculating the fitting slope k of the curve, and substituting the slope k into the fitting curveEquivalent formula for calculating expansion coefficient of metal bar
The linear expansion coefficient alpha of the metal bar is obtained.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A device for measuring the coefficient of linear expansion of a metal, comprising:
the soaking structure is composed of a quartz tube, a heating belt and a heat insulation layer, wherein the heating belt is wound on the outer side of the quartz tube, and a metal rod to be measured is heated in a mode of being placed in the quartz tube and is supported in the quartz tube in a suspended mode;
a thermocouple temperature sensor, wherein a thermocouple probe of the thermocouple temperature sensor is stuck with the metal bar by a heat-resistant adhesive tape and is used for measuring the temperature of the metal bar in real time; and
the first grating displacement sensor consists of a movable end and a fixed end of a grating ruler, is positioned at one axial end of the metal bar to be measured and is used for measuring the expansion displacement of the metal bar,
the grating ruler comprises a grating ruler moving end, wherein heat insulation pieces are arranged at two axial end parts of a metal rod to be measured, and the moving end of the grating ruler is in gapless contact with one axial end part of the metal rod to be measured.
2. The device for measuring linear expansion coefficient of metal according to claim 1, further comprising a second grating displacement sensor composed of a movable end and a fixed end of the grating scale for differentially measuring the amount of expansion displacement of the metal bar, wherein the other axial end of the metal bar to be measured is in gapless contact with the movable end of the grating scale of the second grating displacement sensor.
3. The device for measuring the linear expansion coefficient of a metal according to claim 1, further comprising a pressure-adjustable spring abutting against the moving end of the grating ruler.
4. The device for measuring the linear expansion coefficient of a metal according to claim 1, wherein one axial end of the metal rod to be measured is a fixed end, and the other axial end is a free telescopic end abutting against the movable end of the grating ruler.
5. The device for measuring the linear expansion coefficient of a metal according to claim 1, further comprising a linear slide rail, a first slide block and a second slide block, wherein the soaking structure is arranged on the linear slide rail, and parts at two axial ends of the soaking structure are respectively mounted on the first slide block and the second slide block.
6. The device for measuring the linear expansion coefficient of a metal according to claim 1, further comprising a grating scale display electrically connected with the grating displacement sensor, and the thermocouple probe is electrically connected with a display of the thermocouple temperature sensor, and further comprising a contact-type self-coupling voltage regulator electrically connected with the heating belt.
7. A measuring system of the linear expansion coefficient of a metal, which is characterized by comprising a measuring device, a data processing device and a display device, wherein the measuring device is the measuring device of the linear expansion coefficient of the metal according to any one of claims 1 to 5.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111595895A (en) * | 2020-04-23 | 2020-08-28 | 河南工业大学 | Measuring device and system for linear expansion coefficient of metal |
| CN116399715A (en) * | 2023-06-09 | 2023-07-07 | 天津航天瑞莱科技有限公司 | Aviation pipeline's hot strength test device |
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2020
- 2020-04-23 CN CN202020626127.5U patent/CN212207178U/en not_active Expired - Fee Related
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111595895A (en) * | 2020-04-23 | 2020-08-28 | 河南工业大学 | Measuring device and system for linear expansion coefficient of metal |
| CN116399715A (en) * | 2023-06-09 | 2023-07-07 | 天津航天瑞莱科技有限公司 | Aviation pipeline's hot strength test device |
| CN116399715B (en) * | 2023-06-09 | 2023-08-29 | 天津航天瑞莱科技有限公司 | Aviation pipeline's hot strength test device |
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