Metal thermal expansion coefficient double-end-face measuring method and device

Abstract

The invention discloses a metal thermal expansion coefficient double-end-face measuring method and device, the device comprises a laser light source system, a first interference system, a second interference system, a vacuum tube furnace, a temperature controller, a metal rod, an observation screen and the like, the laser light source system generates laser beams with stable frequency; the first interference system measures the elongation of the metal left end face; the second interference system measures the elongation of the metal right end surface; heating the metal rod in a vacuum tube furnace; the temperature controller realizes heating and temperature control of the vacuum tube furnace; after being heated, the metal rod extends in the axial direction; and the observation screen shows interference fringe swallowing. Starting heating control, recording an actually measured temperature value on the sample and respective swallowing numbers of the circular rings on the first observation screen and the second observation screen in a specific temperature interval, and adding the two ends after temperature measurement is finished to calculate the linear expansion coefficient of the measured metal. According to the double-end-face measuring method and device for the metal thermal expansion coefficient, the vacuum tube furnace is adopted for heating the metal rod, heating is uniform, and the heat preservation performance is good.

Description

Technical Field

[0001] The invention relates to the technical field of metal thermal expansion coefficient detection, in particular to a double-end surface measurement method and device for metal thermal expansion coefficient. Background Art

[0002] When an object is heated, its length, area, volume and other physical quantities will increase. The increase in length is characterized by the expansion coefficient, also known as the linear expansion coefficient. The study of expansion coefficient is widely used in high-temperature manufacturing of refractory materials, building materials, glass, metals, plastics, ceramics, rails, composite materials, etc. For example, expansion joints should be reserved for rails of trains; deformation caused by temperature changes should be considered for key parts of precision instruments; some mechanical parts with large interference in engineering can use the thermal expansion of materials to cooperate with assembly or disassembly, etc.

[0003] At present, the measurement of thermal expansion coefficient of metal mostly adopts single-end method, such as micrometer method, interference ring engulfment counting method, and optical lever method. These methods require that one end of the metal rod to be measured must be fixed, and the free end needs to achieve micro-elongation measurement through contact, embedded reflectors, etc. This will inevitably affect the measurement results. To address the above problems, existing equipment needs to be improved. Summary of the invention

[0004] The purpose of the present invention is to provide a method and device for double-end surface measurement of metal thermal expansion coefficient, so as to solve the problem that the measurement methods proposed in the above background technology require one end of the metal rod to be measured to be fixed, and the free end needs to achieve slight elongation measurement through contact, embedded reflector, etc., which will affect the measurement result.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a double-end-face measuring device for the thermal expansion coefficient of metal, comprising a laser light source system, a first interference system, a second interference system, a vacuum tube furnace, a temperature controller, a metal rod and an observation screen, etc., wherein the laser light source system generates a laser beam with a stable frequency; the first interference system measures the elongation of the left end face of the metal; the second interference system measures the elongation of the right end face of the metal; the vacuum tube furnace heats the metal rod; the temperature controller realizes the heating and temperature control of the vacuum tube furnace; the metal rod elongates axially after being heated; and the observation screen displays the engulfment of interference fringes. Turn on the heating control, record the measured temperature value on the sample and the respective engulfment numbers of the rings on the first and second observation screens within a specific temperature range, and add the two ends after the temperature measurement to calculate the linear expansion coefficient of the measured metal.

[0006] Specifically, the laser light source system consists of a frequency-stabilized laser and a 1*2 optical fiber. The laser emits a frequency-stabilized laser which is divided into two laser beams of equal intensity through the 1*2 optical fiber (splitting ratio is 5:5) and transmitted through the optical fiber.

[0007] Specifically, the first interference system consists of a first beam expanding and converging lens, a first beam splitter (with a beam splitting ratio of 5:5), a first reference mirror and a first observation screen; the point light source formed by the first beam expanding and converging lens is located exactly on the front surface of the first beam splitter.

[0008] Specifically, the first interference system generates concentric rings on the first viewing screen.

[0009] Specifically, the second interference system consists of a second beam expanding and converging lens, a second beam splitter (with a beam splitting ratio of 5:5), a second reference mirror and a second observation screen; the point light source formed by the second beam expanding and converging lens is located exactly on the front surface of the second beam splitter.

[0010] Specifically, the second interference system will generate concentric rings on the second viewing screen.

[0011] Specifically, the first observation screen and the second observation screen can be replaced with a CCD camera.

[0012] Specifically, the vacuum tube furnace is sealed with two layers of glass tubes, the interlayer is evacuated, and a hollow light-transmitting thin film resistance heating design is used. The heating current is adjustable from 0 to 0.6A, and the maximum output voltage is 45V to provide a uniform heating field for the metal being tested.

[0013] Specifically, the vacuum tube furnace is fixed on the furnace frame by a left-end fixing locking mechanism and a right-end fixing locking mechanism, and PT100 input and output and heating current input can be realized.

[0014] Specifically, the temperature controller uses a Pt100 sensor to measure temperature, adjust the heating current of the tube furnace, control the heating rate, and indicate the heating current.

[0015] Specifically, the two end faces of the metal rod to be measured are polished and serve as measuring mirrors of the first interference system and the second interference system respectively; the metal rod is placed in a vacuum tube furnace through an insulation ring and then stretched after being heated, thereby changing the optical path of the measuring arm, causing the first and second interference concentric rings to be engulfed respectively.

[0016] Specifically, a temperature measurement conductive copper block with an embedded PT100 temperature sensor probe is installed in the middle of the metal rod to measure the heated temperature of the metal rod in real time.

[0017] Specifically, a method for measuring the thermal expansion coefficient of a metal by double-end surfaces is provided. The method is based on the device for measuring the thermal expansion coefficient of a metal by double-end surfaces and comprises the following steps: Step 1, vacuum tube furnace installation First, carefully place the metal rod to be tested with the PT100 temperature sensor probe embedded in it into the vacuum tube furnace, so that the PT100 temperature sensor probe is in the middle of the furnace body. Then, fix the vacuum tube furnace on the furnace frame through the left and right fixing locking mechanisms. Finally, connect the input and output terminals of the PT100 probe and the heating current input terminal.

[0018] Step 2: First interference system adjustment When the laser light source is working normally, first carefully adjust the first beam expansion and convergence lens to make the reflected light from the left end of the metal rod return along the original path, then place the first beam splitter, the first reference mirror and the first observation screen in sequence. Finally, adjust the first reference mirror to make a clear concentric ring interference pattern appear on the observation screen.

[0019] Step 3: Adjustment of the second interference system When the laser light source is working properly, first carefully adjust the second beam expansion and convergence lens to make the reflected light from the left end of the metal rod return along the original path, then place the second beam splitter, the second reference mirror and the second observation screen in sequence. Finally, adjust the second reference mirror to make a clear concentric ring interference pattern appear on the observation screen.

[0020] Step 4: Set the temperature controller Turn on the heating control, adjust the heating current, and set the temperature control point.

[0021] Step 5, heating and data recording Turn on the heating control, record the measured temperature value on the sample and the number of engulfments of the rings on the first and second observation screens in a specific temperature range, and add the two ends after the temperature measurement to calculate the linear expansion coefficient of the metal being measured. During the recording process, the change in the temperature of the specimen can be measured according to a certain elongation of the specimen (for example, the optical path difference corresponding to the change of 50 or 100 interference rings); or the elongation of the specimen can be measured by increasing a certain temperature (for example, 5°C or 10°C).

[0022] Compared with the prior art, the invention has the following beneficial effects: the method and device for measuring the thermal expansion coefficient of metal at both ends are: (1) The present invention adopts a double-end measurement structure, innovates and enriches the measurement method of metal thermal expansion coefficient, and adopts a vacuum tube furnace to heat the metal rod, which has uniform heating and good thermal insulation; (2) The present invention adopts optical fiber to guide light, reduces the size of the equipment, improves stability, and uses the polished end face of the metal rod as the reflection surface to realize direct measurement of the metal rod itself, thereby reducing the influence of external equipment, improving measurement accuracy, and realizing free switching between single-end face and double-end face measurement, thereby broadening the application space of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1This is a flow chart of the measurement system of the present invention. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] See also Figure 1 The present invention provides a technical solution: a double-end-face measuring device for the thermal expansion coefficient of metal, comprising a laser light source system, a first interference system, a second interference system, a vacuum tube furnace, a temperature controller, a metal rod and an observation screen, etc., wherein the laser light source system generates a laser beam with a stable frequency; the first interference system measures the elongation of the left end face of the metal; the second interference system measures the elongation of the right end face of the metal; the vacuum tube furnace heats the metal rod; the temperature controller realizes the heating and temperature control of the vacuum tube furnace; the metal rod elongates axially after being heated; and the observation screen displays the engulfment of interference fringes. Turn on the heating control, record the measured temperature value on the sample and the respective engulfment numbers of the rings on the first and second observation screens within a specific temperature range, and add the two ends after the temperature measurement to calculate the linear expansion coefficient of the measured metal.

[0026] A method for measuring the thermal expansion coefficient of a metal on a double-end surface, the method is based on a device for measuring the thermal expansion coefficient of a metal on a double-end surface, and comprises the following steps: Step 1, vacuum tube furnace installation First, carefully place the metal rod to be tested with the PT100 temperature sensor probe embedded in it into the vacuum tube furnace, so that the PT100 temperature sensor probe is in the middle of the furnace body. Then, fix the vacuum tube furnace on the furnace frame through the left and right fixing locking mechanisms. Finally, connect the input and output terminals of the PT100 probe and the heating current input terminal.

[0027] Step 2: First interference system adjustment When the laser light source is working normally, first carefully adjust the first beam expansion and convergence lens to make the reflected light from the left end of the metal rod return along the original path, then place the first beam splitter, the first reference mirror and the first observation screen in sequence. Finally, adjust the first reference mirror to make a clear concentric ring interference pattern appear on the observation screen.

[0028] Step 3: Adjustment of the second interference system When the laser light source is working properly, first carefully adjust the second beam expansion and convergence lens to make the reflected light from the left end of the metal rod return along the original path, then place the second beam splitter, the second reference mirror and the second observation screen in sequence. Finally, adjust the second reference mirror to make a clear concentric ring interference pattern appear on the observation screen.

[0029] Step 4: Set the temperature controller Turn on the heating control, adjust the heating current, and set the temperature control point.

[0030] Step 5, heating and data recording Turn on the heating control, record the measured temperature value on the sample and the number of engulfments of the rings on the first and second observation screens in a specific temperature range, and add the two ends after the temperature measurement to calculate the linear expansion coefficient of the metal being measured. During the recording process, the change in the temperature of the specimen can be measured according to a certain elongation of the specimen (for example, the optical path difference corresponding to the change of 50 or 100 interference rings); or the elongation of the specimen can be measured by increasing a certain temperature (for example, 5°C or 10°C).

[0031] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A double-end surface measuring device for metal thermal expansion coefficient, characterized in that: It includes a laser light source system, a first interference system, a second interference system, a vacuum tube furnace, a temperature controller, a metal rod and an observation screen, wherein the laser light source system generates a laser beam with stable frequency; the first interference system measures the elongation of the left end surface of the metal; the second interference system measures the elongation of the right end surface of the metal; the vacuum tube furnace heats the metal rod; the temperature controller realizes heating and temperature control of the vacuum tube furnace; the metal rod elongates axially after being heated; and the observation screen shows the interference fringes engulfing.

2. A dual-end surface measuring device for metal thermal expansion coefficient according to claim 1, characterized in that: The laser light source system is composed of a frequency-stable laser and a 1*2 optical fiber. The laser emits a frequency-stable laser which is divided into two laser beams with equal intensity through the 1*2 optical fiber and transmitted through the optical fiber.

3. A dual-end surface measuring device for metal thermal expansion coefficient according to claim 1, characterized in that: The first interference system consists of a first beam expanding and converging lens, a first beam splitter, a first reference mirror and a first observation screen; the point light source formed by the first beam expanding and converging lens is exactly located on the front surface of the first beam splitter, and the first interference system will produce concentric rings on the first observation screen, and the second interference system consists of a second beam expanding and converging lens, a second beam splitter, a second reference mirror and a second observation screen; the point light source formed by the second beam expanding and converging lens is exactly located on the front surface of the second beam splitter, and the second interference system will produce concentric rings on the second observation screen.

4. A dual-end surface measuring device for metal thermal expansion coefficient according to claim 3, characterized in that: The first observation screen and the second observation screen are replaced with CCD cameras.

5. A dual-end surface measuring device for metal thermal expansion coefficient according to claim 3, characterized in that: The vacuum tube furnace is sealed with two layers of glass tubes, the interlayer is evacuated, and the hollow light-transmitting film resistance heating design is adopted. The heating current is adjustable from 0 to 0.6A, and the maximum output voltage is 45V to provide a uniform heating field for the metal being tested.

6. A dual-end surface measuring device for metal thermal expansion coefficient according to claim 1, characterized in that: The vacuum tube furnace is fixed on the furnace frame by a left-end fixing locking mechanism and a right-end fixing locking mechanism, so as to realize PT100 input and output and heating current input.

7. A dual-end surface measuring device for metal thermal expansion coefficient according to claim 3, characterized in that: The temperature controller uses a Pt100 sensor to measure temperature, adjust the heating current of the tube furnace, control the heating rate, and indicate the heating current.

8. A dual-end surface measuring device for metal thermal expansion coefficient according to claim 3, characterized in that: The two end faces of the metal rod to be measured are polished and serve as measuring mirrors of the first interference system and the second interference system respectively; the metal rod is placed in a vacuum tube furnace through an insulation ring and then stretched after being heated, thereby changing the optical path of the measuring arm, causing the first and second interference concentric rings to be engulfed respectively.

9. A dual-end surface measuring device for metal thermal expansion coefficient according to claim 3, characterized in that: A temperature measurement conductive copper block with an embedded PT100 temperature sensor probe is installed in the middle of the metal rod to measure the heated temperature of the metal rod in real time.

10. A method for measuring the thermal expansion coefficient of metal by double end surfaces, characterized in that: The method is based on a double-end surface measuring device for metal thermal expansion coefficient according to any one of claims 1 to 9, and comprises the following steps: Step 1, vacuum tube furnace installation First, carefully place the metal rod with the PT100 temperature sensor probe into the vacuum tube furnace, so that the PT100 temperature sensor probe is in the middle of the furnace body. Then, fix the vacuum tube furnace on the furnace frame through the left and right fixing locking mechanisms. Finally, connect the input and output terminals of the PT100 probe and the heating current input terminal. Step 2: First interference system adjustment Under the condition that the laser light source works normally, first carefully adjust the first beam expansion and convergence lens to make the reflected light from the left end face of the metal rod return along the original path, then place the first beam splitter, the first reference mirror and the first observation screen in sequence, and finally adjust the first reference mirror to make a clear concentric ring interference pattern appear on the observation screen; Step 3: Adjustment of the second interference system Under the condition that the laser light source is working normally, first carefully adjust the second beam expansion and convergence lens to make the reflected light from the left end face of the metal rod return along the original path, then place the second beam splitter, the second reference mirror and the second observation screen in sequence, and finally adjust the second reference mirror to make a clear concentric ring interference pattern appear on the observation screen; Step 4: Set the temperature controller Turn on the heating control, adjust the heating current, and set the temperature control point; Step 5, heating and data recording Turn on the heating control, record the measured temperature value on the sample and the respective engulfment numbers of the rings on the first and second observation screens within a specific temperature range, add the two ends after the temperature measurement to calculate the linear expansion coefficient of the measured metal, and during the recording process, measure the change in the temperature of the specimen according to a certain elongation of the specimen; use a method to measure the elongation of the specimen by increasing a certain temperature.

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