阅读说明：本技术 一种材料线膨胀系数测量装置及其方法 (Device and method for measuring linear expansion coefficient of material ) 是由 李琳 刘以声 刘桐 孙晓慧 于 2020-12-31 设计创作，主要内容包括：本发明涉及一种材料线膨胀系数测量装置及其方法,该装置包括相互连接的PC端和温控板,温控板连接有温度传感器和热电制冷器,热电制冷器的顶部和底部贴合安装有传导散热部,保温箱内设置有支架,支架的两端安装有振动电机,待测材料的一端连接有用于测量待测材料尺寸变化的千分表；振动电机通过支架间接提供激振力给待测材料；温控板用于控制热电制冷器产生热量；温度传感器用于采集保温箱内部环境温度数据；传导散热部用于热量传递；PC端用于设置测试温度数据,以及根据待测材料的尺寸变化和保温箱内部环境温度数据,计算得到待测材料的线膨胀系数。与现有技术相比,本发明能够增大可测温度范围、消除材料内部残余应力,提高测量结果的准确性。(The invention relates to a material linear expansion coefficient measuring device and a method thereof, wherein the device comprises a PC end and a temperature control plate which are connected with each other, the temperature control plate is connected with a temperature sensor and a thermoelectric refrigerator, the top and the bottom of the thermoelectric refrigerator are provided with heat conduction and dissipation parts in a fitting manner, a support is arranged in an incubator, two ends of the support are provided with vibrating motors, and one end of a material to be measured is connected with a dial indicator for measuring the size change of the material to be measured; the vibration motor indirectly provides an excitation force to the material to be tested through the bracket; the temperature control plate is used for controlling the thermoelectric refrigerator to generate heat; the temperature sensor is used for acquiring the internal environment temperature data of the heat insulation box; the heat conduction and dissipation part is used for heat transfer; and the PC end is used for setting test temperature data and calculating the linear expansion coefficient of the material to be tested according to the size change of the material to be tested and the temperature data of the environment in the heat insulation box. Compared with the prior art, the invention can enlarge the measurable temperature range, eliminate the residual stress in the material and improve the accuracy of the measurement result.)

1. A material linear expansion coefficient measuring device is characterized by comprising a PC end (1), the PC end (1) is connected with a temperature control plate (2), the temperature control plate (2) is respectively connected with a temperature sensor (3) and a thermoelectric refrigerator (4), the top and the bottom of the thermoelectric refrigerator (4) are respectively attached with a heat conduction and dissipation part, the thermoelectric refrigerator (4) and the conduction heat dissipation part at the bottom thereof are positioned in the closed heat insulation box (5), the heat conduction and dissipation part at the top of the thermoelectric refrigerator (4) is positioned outside the heat preservation box (5), a bracket (7) for placing a material (6) to be tested is arranged in the heat preservation box (5), the two ends of the bracket (7) are provided with vibrating motors (8), the material to be measured (6) is connected with a dial indicator (9), the dial indicator (9) is used for measuring the size change data of the material (6) to be measured;

the vibration motor (8) indirectly provides an excitation force to the material to be tested (6) through the bracket (7) and is used for eliminating the residual stress in the material to be tested (6);

the temperature control board (2) is used for receiving the set test temperature data output by the PC end (1) and controlling the thermoelectric refrigerator (4) to generate corresponding heat; the system is used for receiving the internal environment temperature data of the heat preservation box (5) collected by the temperature sensor (3) and transmitting the internal environment temperature data of the heat preservation box (5) to the PC (personal computer) end (1);

the heat conduction and radiation part is used for conducting heat generated by the thermoelectric refrigerator (4) into the heat insulation box (5) and conducting heat in the heat insulation box (5) to the outside;

and the PC end (1) is used for setting test temperature data by a user and calculating the linear expansion coefficient of the material (6) to be tested according to the size change data of the material (6) to be tested and the internal environment temperature data of the heat preservation box (5).

2. A material linear expansion coefficient measuring device according to claim 1, wherein the heat conducting and dissipating part comprises a heat dissipating base (10) and a fan (11), one side of the heat dissipating base (10) is in contact with the thermoelectric refrigerator (4), and the fan (11) is installed on the other side of the heat dissipating base (10).

3. A material linear expansion coefficient measuring device according to claim 2, characterized in that the heat sink base (10) is embodied as a pure copper heat sink base.

4. A material linear expansion coefficient measuring device according to claim 1, characterized in that the temperature control plate (2) is connected with a switching power supply (12).

5. A material linear expansion coefficient measuring device according to claim 1, wherein the thermal control plate (2) is connected to the PC terminal (1) via an RS232 transmission line.

6. A material linear expansion coefficient measuring device according to claim 1, characterized in that the thermo-electric refrigerator (4) is embodied as a semiconductor TEC 1-12708.

7. A device for measuring the linear expansion coefficient of a material according to claim 1, characterized in that the temperature sensor (3) is embodied as an NTC temperature sensor, the probe of which is located in the incubator (5), and the other end of which is connected to the temperature control plate (2).

8. A material linear expansion coefficient measuring device according to claim 1, characterized in that said vibration motor (8) is embodied as a Nidec micro vibration motor.

9. A device for measuring the linear expansion coefficient of a material according to claim 1, characterized in that the thermal insulation box (5) is made of aluminum silicate fiber thermal insulation paper and polyethylene multi-layer pipe thermal insulation material.

10. A method for measuring a coefficient of linear expansion of a material using the device for measuring a coefficient of linear expansion of a material according to claim 1, comprising the steps of:

s1, placing the material to be tested on a support inside the heat preservation box, connecting a dial indicator to one end of the material to be tested, and enabling a dial plate of the dial indicator to be located outside the heat preservation box;

s2, setting a test temperature value at the PC end by the user, and transmitting the test temperature data to the temperature control board by the PC end;

s3, controlling the thermoelectric refrigerator to generate corresponding heat by the temperature control plate according to the test temperature data, and conducting the heat to the interior of the heat preservation box by the conduction and heat dissipation part so as to heat the material to be tested in the heat preservation box and enable the material to be tested to be heated uniformly;

s4, adopting a cyclic loading mode, and indirectly providing an exciting force to the material to be tested through a bracket by a vibration motor so as to eliminate the residual stress in the material to be tested;

s4, the PC end receives the data of the internal environment temperature of the incubator collected by the temperature sensor in real time through the temperature control board;

and S5, when the temperature data of the environment in the heat preservation box is stable, the user inputs the size change data of the material to be measured by the dial indicator to the PC end, and the PC end combines the size change data of the material to be measured and the temperature data of the environment in the heat preservation box to calculate the linear expansion coefficient of the material to be measured.

Technical Field

The invention relates to the technical field of material parameter measurement, in particular to a device and a method for measuring a material linear expansion coefficient.

Background

The linear expansion coefficient is one of the important mechanical properties of metal and nonmetal materials, and specifically refers to the change of a solid material in a linear direction along with the change of temperature. The linear expansion coefficient of the material is closely related to the distribution of the thermal stress in the material and key parameters of the total size structure design calculation, and the influence of the matching and difference of the linear expansion coefficient on the structure and the performance of the material is considered when the linear expansion coefficient of the material is measured.

The current method for measuring the linear expansion coefficient of the material mainly comprises the following steps: a flowing water heating method, a steam heating method, an electric heating method, and the like. Among them, the electric heating method is widely used because of its advantages such as easy and simple to handle, rapid heating, and can measure under multiple temperature working points, its disadvantage is that the temperature change is influenced by the environment, for example, the heating temperature of the solid linear expansion coefficient measuring instrument in the laboratory needs to be controlled between 80 ℃, so that the linear expansion coefficient of some materials is measured by the electric heating generator is limited; secondly, when some materials to be measured are heated, the internal composition characteristics of the materials can generate residual stress, which easily causes large errors in measurement and even can not be performed.

Disclosure of Invention

The present invention is directed to overcome the above-mentioned drawbacks of the prior art, and an object of the present invention is to provide a device and a method for measuring a linear expansion coefficient of a material, so as to provide a wider range of temperature control, and simultaneously eliminate the residual stress of the material during the measurement process, thereby ensuring the accuracy of the measurement result.

The purpose of the invention can be realized by the following technical scheme: a material linear expansion coefficient measuring device comprises a PC end, wherein the PC end is connected with a temperature control plate, the temperature control plate is respectively connected with a temperature sensor and a thermoelectric refrigerator, the top and the bottom of the thermoelectric refrigerator are respectively attached with a conduction heat dissipation part, the thermoelectric refrigerator and the conduction heat dissipation part at the bottom of the thermoelectric refrigerator are positioned in a closed heat insulation box, the conduction heat dissipation part at the top of the thermoelectric refrigerator is positioned outside the heat insulation box, a support for placing a material to be measured is arranged in the heat insulation box, two ends of the support are provided with vibrating motors, the material to be measured is connected with a dial indicator, and the dial indicator is used for measuring size change data of the material to be measured;

the vibration motor indirectly provides an excitation force to the material to be detected through the bracket and is used for eliminating the residual stress in the material to be detected;

the temperature control board is used for receiving the set test temperature data output by the PC end and controlling the thermoelectric refrigerator to generate corresponding heat; the system comprises a PC terminal, a temperature sensor, a data processing module and a data processing module, wherein the PC terminal is used for receiving the data of the internal environment temperature of the heat preservation box acquired by the temperature sensor and transmitting the data of the internal environment temperature of the heat preservation box to the PC terminal;

the heat conduction and radiation part is used for conducting heat generated by the thermoelectric refrigerator into the heat insulation box and conducting the heat in the heat insulation box to the outside;

and the PC end is used for setting test temperature data by a user and calculating the linear expansion coefficient of the material to be tested according to the size change data of the material to be tested and the temperature data of the environment in the heat insulation box.

Furthermore, the conduction heat dissipation part comprises a heat dissipation base and a fan, one surface of the heat dissipation base is in contact with the thermoelectric refrigerator, and the fan is installed on the other surface of the heat dissipation base.

Further, the heat dissipation base is specifically a pure copper heat dissipation base.

Further, the temperature control plate is connected with a switching power supply.

Further, the temperature control board is connected with the PC end through an RS232 transmission line.

Further, the thermoelectric cooler is specifically a semiconductor TEC 1-12708.

Further, the temperature sensor is specifically an NTC temperature sensor, a probe of the NTC temperature sensor is located in the heat insulation box, and the other end of the NTC sensor is connected to the temperature control plate.

Further, the vibration motor is specifically a Nidec micro vibration motor.

Furthermore, the heat preservation box adopts aluminum silicate fiber heat insulation paper and polyethylene multilayer pipe heat preservation materials.

Furthermore, rubber and plastic foam cotton is laid in the heat insulation box.

A method for measuring the linear expansion coefficient of a material comprises the following steps:

s1, placing the material to be tested on a support inside the heat preservation box, connecting a dial indicator to one end of the material to be tested, and enabling a dial plate of the dial indicator to be located outside the heat preservation box;

s2, setting a test temperature value at the PC end by the user, and transmitting the test temperature data to the temperature control board by the PC end;

s3, controlling the thermoelectric refrigerator to generate corresponding heat by the temperature control plate according to the test temperature data, and conducting the heat to the interior of the heat preservation box by the conduction and heat dissipation part so as to heat the material to be tested in the heat preservation box and enable the material to be tested to be heated uniformly;

s4, adopting a cyclic loading mode, and indirectly providing an exciting force to the material to be tested through a bracket by a vibration motor so as to eliminate the residual stress in the material to be tested;

s4, the PC end receives the data of the internal environment temperature of the incubator collected by the temperature sensor in real time through the temperature control board;

and S5, when the temperature data of the environment in the heat preservation box is stable, the user inputs the size change data of the material to be measured by the dial indicator to the PC end, and the PC end combines the size change data of the material to be measured and the temperature data of the environment in the heat preservation box to calculate the linear expansion coefficient of the material to be measured.

Compared with the prior art, the invention has the following advantages:

firstly, the PC end and the temperature control board which are connected with each other are arranged, the temperature control board is respectively connected with the temperature sensor and the thermoelectric refrigerator, the thermoelectric refrigerator is controlled by the temperature control board to generate heat corresponding to test temperature data, and then the heat is conducted into the heat insulation box through the conduction heat dissipation part.

Secondly, the support for placing the material to be measured is arranged in the heat preservation box, the vibration motors are arranged at two ends of the support, after the vibration motors are electrified to work, exciting force can be indirectly provided for the material to be measured through the support, the material to be measured resonates under the action of cyclic loading, the internal stress field of the material is changed, the stress distribution is homogenized, the residual stress is released, the internal residual stress of the material can be effectively eliminated, the measurement error is reduced, and the accuracy of the measurement result is improved.

Drawings

FIG. 1 is a schematic diagram of the apparatus of the present invention;

FIG. 2 is a schematic diagram of the operating principle of the semiconductor TEC;

FIG. 3 is a schematic view of the connection of a thermal control plate;

the notation in the figure is: 1. the device comprises a PC terminal, 2, a temperature control board, 3, a temperature sensor, 4, a thermoelectric refrigerator, 5, an insulation box, 6, a material to be measured, 7, a bracket, 8, a vibration motor, 9, a dial indicator, 10, a heat dissipation base, 11, a fan, 12 and a switching power supply.

Detailed Description

The invention is described in detail below with reference to the figures and specific embodiments.

Examples

As shown in fig. 1, a material linear expansion coefficient measuring device comprises a PC end 1, the PC end 1 is connected with a temperature control plate 2 through an RS232 transmission line, the temperature control plate 2 is respectively connected with a temperature sensor 3 and a thermoelectric refrigerator 4, and the temperature control plate 2 is connected with a switching power supply 12;

the top and the bottom of the thermoelectric refrigerator 4 are respectively provided with a conduction heat dissipation part in a fitting manner, the conduction heat dissipation part comprises a heat dissipation base 10 and a fan 11, one surface of the heat dissipation base 10 is in contact with the thermoelectric refrigerator 4, and the fan 11 is arranged on the other surface of the heat dissipation base 10;

thermoelectric refrigerator 4 and the conduction heat dissipation part of bottom are located inclosed insulation can 5, and the conduction heat dissipation part at thermoelectric refrigerator 4 top is located the insulation can 5 outside, is provided with in the insulation can 5 to be used for placing the support 7 of material 6 that awaits measuring, and vibrating motor 8 is installed to the both ends of support 7, and the material 6 that awaits measuring is connected with amesdial 9.

In the structure of the device, the dial indicator 9 is used for measuring the size change data of the material 6 to be measured;

the vibration motor 8 indirectly provides an excitation force to the material 6 to be tested through the bracket 7, and is used for eliminating the residual stress in the material 6 to be tested;

the temperature control board 2 is used for receiving the set test temperature data output by the PC end 1 and controlling the thermoelectric refrigerator 4 to generate corresponding heat; the system is used for receiving the internal environment temperature data of the heat preservation box 5 collected by the temperature sensor 3 and transmitting the internal environment temperature data of the heat preservation box 5 to the PC terminal 1;

the heat-conducting and radiating part is used for conducting heat generated by the thermoelectric refrigerator 4 into the heat-insulating box 5 and conducting heat in the heat-insulating box 5 to the outside;

the PC terminal 1 is used for setting test temperature data by a user and calculating the linear expansion coefficient of the material 6 to be tested according to the size change data of the material 6 to be tested and the internal environment temperature data of the heat insulation box 5.

The thermoelectric refrigerator 4 specifically uses a semiconductor TEC1-12708, and specific parameters of the semiconductor TEC1-12708 are shown in Table 1:

TABLE 1

Index (I)	Specific parameters
		Overall dimension	40mm×40mm×3.5mm
Internal resistance R/omega	1.5～1.8
		Maximum temperature difference delta Tmax(Qc＝0)/K	>67
Maximum operating current Imax(at rated voltage start)/A	8
		DC rated voltage U/V	12
Maximum refrigeration power Qcmax/kW	77
		Maximum rated voltage Umax/V	15.5
Working environment temperature T/° C	-15～83

The specific working principle of the semiconductor TEC is shown in FIG. 2, the semiconductor TEC can achieve the heating purpose by refrigerating or reversing polarity, current carriers (electrons and holes) flow through nodes to cause potential energy change so as to transfer energy, in a heating system, the flow direction of heat is from a temperature control target to a cold surface and a hot surface of the TEC, then to a heat dissipation base, and finally to the ambient air dissipated from the heat dissipation base, and the heat is conducted to the air in an insulation can through a fan to be heated, so that a heat circulation closed box body is formed, and the material to be measured is uniformly heated.

In this embodiment, the temperature sensor 3 is an NTC temperature sensor, which is a thermistor of 10K Ω essentially, a probe of the NTC temperature sensor is located in the incubator 5, the other end of the NTC sensor is connected to the temperature control plate 2, and the NTC temperature sensor measures the ambient temperature in the incubator to determine whether the heating environment in the incubator is balanced. As shown in fig. 3, the specific connection diagram of the thermal control plate 2 is such that the execution unit is controlled by the semiconductor TEC, the operation amount at this time is the heating power, the controlled object is the air in the thermal insulation box, and the temperature is measured as the temperature in the thermal insulation box. In the actual measurement process, the process temperature can be automatically controlled by adopting a proportional-integral-derivative (PID) regulation technology, the output of an integral regulation term is in direct proportion to the integral of deviation to time, and as long as the system has deviation, the integral regulation action is continuously accumulated and a regulation quantity is output to eliminate the deviation. The output of the differential regulation term is in direct proportion to the change rate of the deviation to the time, the differential regulation term hinders the change of the temperature, the overshoot can be reduced, when the system is disturbed, the system can quickly respond, and the effects of reducing the regulation time and improving the stability of the system are achieved.

In order to eliminate the internal residual stress of the material to be measured, the vibration motor 8 is added, and a Nidec miniature vibration motor is selected in the embodiment, and the parameters are shown in table 2. The residual stress in the material to be tested can be effectively eliminated during vibration, the material to be tested resonates under the action of the exciting force through cyclic loading, so that alternating stress is generated, tiny plastic deformation is caused, the original stress field of the material is changed during vibration, the stress distribution is homogenized, the residual stress is released, meanwhile, the stress peak value is reduced, new balance is achieved under a lower stress level, the material is strengthened, the elastic working area of the structure is increased, the size of the material tends to be in a stable state, and the linear expansion coefficient of the material to be tested is obtained through calculation according to dial indicator reading and the temperature data of the environment of the heat insulation box received by a PC (personal computer) end.

TABLE 2

Index (I)	Specific parameters
		Motor specification	21mm×25mm
Operating voltage/V	6～12
		Operating Current/A	0.1

In addition, in order to guarantee good heat conduction effect, heat dissipation base 10 specifically is pure copper heat dissipation base, in this embodiment, pure copper heat dissipation base size is 70 67 × 25mm, in order to guarantee good sealed and heat preservation effect in the insulation can, the insulation can adopts aluminium silicate fiber thermal-insulated paper and polyethylene multilayer pipe insulation material, installation buffer gasket and foam material around the support in the insulation can, in order to play the damping effect to the support in the insulation can, can prevent to produce structural damage to whole device, the inside rubber and plastic foaming cotton that has still laid of insulation can among the practical application, still can scribble the silica gel at each junction of device and externally tie up polytetrafluoroethylene raw material area after, in order to further improve heat preservation and reinforcement effect.

The measuring device provided by the invention is applied to practice, and the specific measuring process comprises the following steps:

s1, placing the material to be tested on a support inside the heat preservation box, connecting a dial indicator to one end of the material to be tested, and enabling a dial plate of the dial indicator to be located outside the heat preservation box;

s2, setting a test temperature value at the PC end by the user, and transmitting the test temperature data to the temperature control board by the PC end;

s3, controlling the thermoelectric refrigerator to generate corresponding heat by the temperature control plate according to the test temperature data, and conducting the heat to the interior of the heat preservation box by the conduction and heat dissipation part so as to heat the material to be tested in the heat preservation box and enable the material to be tested to be heated uniformly;

s4, adopting a cyclic loading mode, and indirectly providing an exciting force to the material to be tested through a bracket by a vibration motor so as to eliminate the residual stress in the material to be tested;

s4, the PC end receives the data of the internal environment temperature of the incubator collected by the temperature sensor in real time through the temperature control board;

and S5, when the temperature data of the environment in the heat preservation box is stable, the user inputs the size change data of the material to be measured by the dial indicator to the PC end, and the PC end combines the size change data of the material to be measured and the temperature data of the environment in the heat preservation box to calculate the linear expansion coefficient of the material to be measured.

The specific process of the embodiment applying the device and the method comprises the following steps:

1. and (3) opening the HyperTerminal at the PC end, connecting the TCB temperature control board connected with the switching power supply with the PC end through an RS232 transmission line, and connecting the NTC temperature sensor and the TEC semiconductor wafer at the corresponding position of the TCB temperature control board.

2. The fan and the pure copper heat dissipation base are assembled to form two heat conduction and dissipation parts. And then the conduction and heat dissipation parts are respectively arranged at the upper end and the lower end of the semiconductor TEC sheet and are fixed by silica gel. One of the heat-conducting and radiating parts is arranged inside the heat-insulating box and can realize the heating function, and the other heat-conducting and radiating part is arranged outside the heat-insulating box and can ensure that the whole heat radiation of the equipment is good.

3. Install the amesdial additional with the one end of the material that will choose for use to be measured, install two small-size direct current vibrating motor respectively on the support at the object both ends that await measuring, the vibrating motor circular telegram back is through the indirect vibration material that awaits measuring of support, reaches the purpose of eliminating residual stress to install buffer spacer and foam around the support in the incubator, in order to prevent to produce structural destruction to whole device.

4. Rubber and plastic foam cotton is paved in the heat preservation box, and a polytetrafluoroethylene raw material belt is externally bound after silica gel is coated at each joint of the device, so that the heat preservation and reinforcement effects are achieved.

5. And setting the temperature of the PC end, pulling a power switch, reading and recording a dial indicator when the environment temperature in the heat insulation box is stable, and calculating the linear expansion coefficient of the material to be measured by the PC end.

In conclusion, the technical scheme provided by the invention effectively solves the limitation of the heating temperature range of the traditional device, and not only can the linear expansion coefficient of a single material be measured, but also the linear expansion coefficient of the composite material can be measured. Specifically, the method comprises the following steps:

the vibration motor is used for exciting vibration, the influence on data measurement is relatively small, the error variation range is +/-0.001-0.002 mm, the residual stress of the material is eliminated through cyclic loading, and the more accurate linear expansion coefficient measurement of the composite material is realized;

the time required by temperature control is shorter, the temperature fluctuation is small, the precision is high, and compared with the existing SLE-1 solid linear expansion coefficient tester, the temperature precision of the improved device is improved from 0.1 ℃ to 0.01 ℃;

the used semiconductor TEC can be used for refrigerating and heating by polarity reversal, the measurable temperature range is increased, the measured temperature can be controlled to be 10-60 ℃, and corresponding data can be obtained even if the temperature is lower than room temperature;

the safety is improved, the device of the tested material is damped by installing the buffer gasket and the foam material, and the structural damage to the experimental device can be prevented;

compared with the existing SLE-1 solid linear expansion coefficient tester, the original heat-insulating material polyvinyl chloride (PVC) pipe is changed into aluminum silicate fiber heat-insulating paper, a polyethylene multilayer pipe and the like;

the data display is accurate, and the structural device is fixed and precise.