CN106153670A - A kind of linear expansion coefficient measuring instrument based on Hall effect - Google Patents

Abstract

The invention discloses a linear expansion coefficient measuring instrument based on the Hall effect, which includes a heating module and a deformation measurement module. Components, control circuits, display screens. It is characterized in that: one end of the metal rod to be tested is fixed, and the other end is in contact with the lever; one end of the lever is fixed, and the other end is provided with a Hall element; the position of the Hall element is in a linear gradient magnetic field ; The gradient magnetic field is placed opposite to each other by two identical magnets. The measuring instrument uses two physical methods of lever and Hall effect to amplify the small deformation of the material to be measured in two stages, and realizes the accurate measurement of the linear expansion coefficient. The invention has simple measurement process, intuitive and obvious reading, easy installation and operation, low cost and accurate measurement result.

Description

A Linear Expansion Coefficient Measuring Instrument Based on Hall Effect

technical field

The invention relates to the field of physical experiment devices, in particular to an experiment instrument for accurately measuring the linear expansion coefficient of solid materials.

Background technique

The coefficient of linear expansion is one of the basic physical properties of solid materials. When the temperature of the object changes, the linear dimensions of the solid material will change with the change of temperature. Typically, as the temperature increases, the size of the solid material will increase. In the design and manufacture of various engineering structures and precision instruments, the linear expansion coefficients of different materials need to be considered, so it is of great significance to measure the linear expansion coefficients of solid materials. Common methods for measuring linear expansion coefficient include optical lever method, interferometry, etc. These methods amplify the deformation of solid materials through optical methods to measure the linear expansion coefficient.

Although the result of measuring linear expansion coefficient by optical method is more accurate, the measurement operation process is relatively cumbersome. The main problems are: (1) The adjustment process is complicated. Device adjustments for optical measurements are generally demanding. For example: the optical lever law needs to observe the image of the scale in the telescope; the interference law needs to fine-tune the angular position of the optical mirror to make the two beams of light interfere. If it cannot be adjusted accurately to meet the experimental requirements, large errors will occur. (2) The readings are inaccurate and prone to errors. Optical methods are generally more difficult to read. The measurement of the coefficient of linear expansion is to read the deformation of the material during the heating process. Whether it is reading the scale of the scale or changing the number of interference fringes, there are large errors, and it is very easy to read data errors.

To sum up, the traditional optical method is more complicated to measure, the phenomenon is not obvious enough, and the measurement has a large error.

Contents of the invention

In order to overcome the deficiencies of the prior art, the present invention provides a linear expansion coefficient measuring instrument based on the Hall effect. During the measurement process, the data reading is intuitive and obvious, the measurement result is accurate, the operation is simple and easy to adjust, and the cost is low.

The technical scheme adopted in the present invention is: a linear expansion coefficient measuring instrument based on the Hall effect, including a metal rod to be tested, a heater, a temperature sensor is installed in the heater, and the connected temperature display screen can display the temperature of the metal to be tested in real time. The temperature of the rod; one part of the metal rod to be tested is fixed, and the other end is in contact with the lever. The other end of the lever is provided with a Hall element. The Hall element is placed between two magnets and connected with the control circuit and the display screen.

Compared with the prior art, the advantages and beneficial effects of the present invention are: firstly, the present invention amplifies the deformation of the metal material after thermal expansion through the lever, and then uses the change of the position of the Hall element in the gradient magnetic field to adjust the moving distance of the lever. Measurement, and then read the Hall voltage very intuitively, and finally calculate the thermal expansion deformation and linear expansion coefficient of the metal material according to the proportional coefficient of the lever and the sensitivity of the Hall element. The experimental effect of this method is obvious and intuitive, the operation is simple, and the measurement result is accurate, which can provide a reference for the measurement of the linear expansion coefficient of metal materials or the physics experiment project of colleges and universities.

Description of drawings

Fig. 1 is a structural schematic diagram of the present invention.

Fig. 2 is a structural schematic diagram of 1 in the present invention.

In the figure, 1. heater, 2. temperature sensor, 3. metal rod to be tested, 4. lever, 5. temperature display screen, 6. magnet, 7. hall element, 8. control circuit, 9. display screen, 10. Heating resistance sheet, 11. Heat conduction aluminum block, 12. Insertion port of metal rod to be tested.

detailed description

Below in conjunction with example, further illustrate the present invention.

Referring to Fig. 1, the present invention comprises heater 1, and temperature sensor 2, metal bar 3 to be tested are installed in the heater, and temperature sensor 2 is connected with temperature display screen 5; One end of metal bar to be tested is fixed, and the other end contacts with lever 4, One end of the lever 4 is fixed, and the other end is equipped with a Hall element 7. The position of the Hall element 7 is in the gradient magnetic field generated by two oppositely placed magnets 6 of the same pole. The Hall element 7 is connected with the control circuit 8 and the display screen 9. .

When measuring, turn on the heater 1 power supply, the heater starts to heat the metal rod 3 to be measured, the temperature of the metal rod 3 to be measured can be measured in real time by the temperature sensor 2, and the temperature before heating, heating temperature after completion.

One end of the metal rod 3 to be tested is fixed, and the other end is in contact with the lever 4. When the metal rod 3 to be tested is heated and deformed, the deformation is transmitted to the lever 4, and the lever 4 will rotate around the fixed end, thereby making the Hall element 7 at one end of the lever The position in the gradient magnetic field changes.

According to the Hall effect, when the position of the Hall element 7 in the gradient magnetic field changes, and the magnetic field on the Hall element changes, the generated Hall voltage changes accordingly, and the Hall voltage is proportional to the magnetic field. The magnetic field is proportional to the position, so the output Hall voltage is proportional to the position of the Hall element 7 , and the proportional coefficient is the sensitivity of the Hall element 7 . The Hall voltage output by the Hall element 7 is converted and displayed on the display screen 9 through the control circuit 8, which can be read intuitively.

After the sensitivity conversion of the read Hall voltage, the moving distance of the Hall element 7 can be calculated, and then the deformation of the metal rod 3 to be measured can be calculated through the conversion of the lever proportional coefficient. The linear expansion coefficient can be calculated by bringing the previously read temperature change and the calculated deformation into the linear expansion coefficient formula.

The invention has the advantages of simple experimental measurement process, intuitive and obvious reading, easy installation and operation, and low cost. The measuring instrument amplifies the small deformation of the material to be measured through two physical methods of lever and Hall effect, and realizes the accurate measurement of the linear expansion coefficient. The present invention can provide and carry out in-depth instrument function expansion.

Claims (4)

1. A linear expansion coefficient measuring instrument based on the Hall effect, comprising a heating module and a deformation measurement module, wherein: the heating module is used to heat the material to be measured; Measure the expansion deformation of the material. 2. A linear expansion coefficient measuring instrument based on the Hall effect according to claim 1, characterized in that: the heating module includes upper and lower layers of heating resistance wire heating, a heat transfer aluminum block, a temperature sensor, and a temperature display Screen. 3. A linear expansion coefficient measuring instrument based on Hall effect according to claim 1, characterized in that: the deformation measurement module includes a lever, a Hall element, a magnet, a control circuit, and a display screen. 4. The working method of a linear expansion coefficient measuring instrument based on the Hall effect according to claim 1: it is characterized in that the following steps: 1. install the material to be tested, turn on the heating module power supply, set the heating target temperature, and display it through the temperature The screen displays the current temperature of the material to be tested; ②During the heating process, the material to be tested is heated and expanded, pushing the lever to rotate, causing the displacement of the Hall element and generating different Hall voltages, which are displayed on the screen; ③According to the display on the screen The Hall voltage, referring to the sensitivity of the Hall element, can calculate the linear expansion coefficient of the material to be tested.