Material resistivity measuring device based on ultrasonic detection technology

Abstract

The utility model provides a material resistivity measuring device based on an ultrasonic testing technology, and belongs to the field of ultrasonic nondestructive testing. Sine wave signals of a low-frequency signal generator are converted into ultrasonic signals through an ultrasonic transducer transmitting end to be transmitted; the ultrasonic transducer receiving end is moved along the sliding rail, the ultrasonic transducer receiving end receives an ultrasonic signal transmitted by the ultrasonic transducer transmitting end while the resistance wire to be measured is stretched, converts the ultrasonic signal into an electric signal and inputs the electric signal into the oscilloscope to display the periodic change process of a Lissajous figure in the stretching process of the resistance wire to be measured. And converting the length change into the periodic change of the Lissajous image, calculating the resistance variation before and after the length change of the to-be-measured resistance wire according to the periodic change of the Lissajous image, and further calculating the resistivity of the to-be-measured resistance wire. The resistance wire to be measured is stretched, the resistivity of the resistance wire is calculated according to the results displayed by various testing instruments in the stretching process, operation and observation are easy, and the measurement precision is high.

Description

Technical Field

[0001] This application relates to the technical field of ultrasonic non-destructive testing, and particularly to a device for measuring the resistivity of materials based on ultrasonic testing technology. Background Art

[0002] Resistivity is a physical quantity used to represent the resistance characteristics of various substances, and is an index for measuring the ability of a material to resist the flow of current. It is an inherent property of the material, describing the resistance to the flow of current per unit length, area or volume. The measurement methods of resistivity include the multimeter method, the bridge method, the volt-ampere method, etc., but each has limitations. For example, the accuracy of the resistance value measured by the multimeter method is not high, resulting in a large measurement error in the resistivity measurement. In the volt-ampere method measurement, there are large measurement errors in the measured values of the voltmeter and ammeter, resulting in a large measurement error in the resistivity measurement, and there are many limiting factors, which need to be solved urgently. Utility Model Content

[0003] This application provides a device for measuring the resistivity of materials based on ultrasonic testing technology. A stable stretching device is used to stretch the resistance wire to be measured, and by observing the display results of various test instruments, recording data and calculating, it is easy to operate and observe, with high measurement accuracy, so as to accurately measure the resistivity of the material.

[0004] This application provides a device for measuring the resistivity of materials based on ultrasonic testing technology, including: a low-frequency signal generator, an oscilloscope, an ultrasonic transducer transmitting end, a material fixing member, an ultrasonic transducer receiving end, and a resistance measurement bridge;

[0005] The low-frequency signal generator is used to generate a sine wave signal;

[0006] The ultrasonic transducer transmitting end is connected to the first port of the low-frequency signal generator, converts the sine wave signal into an ultrasonic wave signal, and emits the ultrasonic wave signal;

[0007] One end of the material fixing member is fixed on the bottom plate, and the other end is connected to the ultrasonic transducer receiving end. The material fixing member is used to fix both ends of the resistance wire to be measured;

[0008] The ultrasonic transducer receiving end is arranged on the slide rail of the bottom plate, and while stretching the resistance wire to be measured by moving along the slide rail, it receives the ultrasonic wave signal emitted by the ultrasonic transducer transmitting end;

[0009] The resistance measurement bridge is connected to the resistance wire to be measured and is used to measure the resistance of the resistance wire to be measured during the stretching process;

[0010] The first channel of the oscilloscope is connected to the receiving end of the ultrasonic transducer, and the second channel is connected to the second port of the low-frequency signal generator, which is used to display the periodic change process of the Lissajous figure during the stretching process of the resistance wire to be measured. The change in the length of the resistance wire to be measured is reflected by the periodic change of the Lissajous figure, and then the resistance change amount before and after the length change of the resistance wire to be measured is calculated. Combining the change period of the Lissajous figure, the self-parameters of the resistance wire to be measured, and the resistance change amount, the resistivity of the resistance wire to be measured is calculated according to the resistivity calculation formula.

[0011] Optionally, in the present application, the device further includes:

[0012] A slide table arranged on the slide rail, and the receiving end of the ultrasonic transducer is fixed on the slide table.

[0013] Optionally, in the present application, the material fixing member includes a left fixing clamp and a right fixing clamp. The left fixing clamp is fixed on the left fixing plate at one end of the bottom plate, and the right fixing clamp is fixed on the slide table of the slide rail.

[0014] Optionally, in the present application, the device further includes:

[0015] A winch, which is fixed at one end of the bottom plate and is connected to the slide table on the slide rail. By rotating the rotary handwheel on the winch, the slide table is driven to move along the slide rail.

[0016] Optionally, in the present application, the resistance measuring bridge is a double-arm bridge or a single-arm bridge.

[0017] The material resistivity measuring device based on ultrasonic detection technology in the present application converts the sine wave signal generated by the low-frequency signal generator through the transmitting end of the ultrasonic transducer, converts the electrical signal into an ultrasonic signal for transmission; moves the receiving end of the ultrasonic transducer along the slide rail, while stretching the resistance wire to be measured, the receiving end of the ultrasonic transducer receives the ultrasonic signal transmitted by the transmitting end of the ultrasonic transducer, and converts the ultrasonic signal into an electrical signal and inputs it into the oscilloscope to display the periodic change process of the Lissajous figure during the stretching process of the resistance wire to be measured. The present application does not need to measure the length change of the resistance wire to be measured, converts the length change into the periodic change of the Lissajous figure, and then calculates the resistance change amount before and after the length change of the resistance wire to be measured according to the periodic change of the Lissajous figure. Combining the change period of the Lissajous figure, the self-parameters of the resistance wire to be measured, and the resistance change amount, the resistivity of the resistance wire to be measured is calculated according to the resistivity calculation formula. The present application has the advantages of a wide range of measured objects, large detection depth, accurate defect positioning, high detection sensitivity, low cost, convenient use, fast speed, harmless to the human body, and convenient for on-site use.

[0018] Additional aspects and advantages of the present application will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present application. Description of the Drawings

[0019] The above-mentioned and / or additional aspects and advantages of the present application will become apparent and be readily understood from the following description of embodiments in conjunction with the drawings, wherein:

[0020] Figure 1 Schematic structural diagram of a material resistivity measuring device based on ultrasonic detection technology according to an embodiment of the present application;

[0021] Figure 2 Schematic diagram of the periodic change process of a graph when the Lissajous figure frequency is 1:1 in an embodiment of the present application.

[0022] Description of reference numerals in the drawings: Description of reference numerals: 1 - low-frequency signal generator; 2 - oscilloscope; 3 - ultrasonic transducer transmitting end; 4 - left fixing plate; 5 - left fixing clamp; 6 - resistance measuring bridge; 7 - bottom plate; 8 - sliding table; 9 - slide rail; 10 - winch; 11 - right fixing clamp; 12 - ultrasonic transducer receiving end. Detailed Description of the Embodiment

[0023] Embodiments of the present application will be described in detail below. Examples of the embodiments are shown in the drawings, where the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are intended to explain the present application, and should not be construed as limiting the present application.

[0024] Figure 1 Schematic structural diagram of a material resistivity measuring device based on ultrasonic detection technology according to an embodiment of the present application.

[0025] As Figure 1 shown, the material resistivity measuring device based on ultrasonic detection technology includes: a low-frequency signal generator 1, an oscilloscope 2, an ultrasonic transducer transmitting end 3, a material fixing member, a resistance measuring bridge 6, and an ultrasonic transducer receiving end 12.

[0026] The low-frequency signal generator 1 is used to generate a sine wave signal.

[0027] The ultrasonic transducer transmitting end 3 is connected to the first port of the low-frequency signal generator 1, converts the sine wave signal into an ultrasonic wave signal, and transmits the ultrasonic wave signal.

[0028] One end of the material fixing member is fixed on the bottom plate 7, and the other end is connected to the ultrasonic transducer receiving end 12. The material fixing member is used to fix both ends of the resistance wire to be measured.

[0029] The receiving end 12 of the ultrasonic transducer is arranged on the slide rail 9 of the bottom plate 7. While stretching the resistance wire to be measured by moving along the slide rail 9, it receives the ultrasonic signal emitted by the transmitting end 3 of the ultrasonic transducer.

[0030] The resistance measurement bridge 6 is connected to the resistance wire to be measured and is used to measure the resistance of the resistance wire to be measured during the stretching process.

[0031] The first channel of the oscilloscope 2 is connected to the receiving end 12 of the ultrasonic transducer, and the second channel is connected to the second port of the low-frequency signal generator 1. It is used to display the periodic change process of the Lissajous figure during the stretching process of the resistance wire to be measured. The length change of the resistance wire to be measured is reflected by the periodic change of the Lissajous figure. Furthermore, the resistance change amount before and after the length change of the resistance wire to be measured is calculated. Combining the change period of the Lissajous figure, the self-parameters of the resistance wire to be measured, and the resistance change amount, the resistivity of the resistance wire to be measured is calculated according to the resistivity calculation formula.

[0032] This application does not need to measure the length of the resistance wire to be measured before and after stretching, reduces the influence of low length measurement accuracy on the calculation result, and improves the measurement accuracy of resistivity.

[0033] Optionally, in the embodiment of the present application, the measuring device further includes:

[0034] A slide table 8 arranged on the slide rail 9, and the receiving end 12 of the ultrasonic transducer is fixed on the slide table 8.

[0035] Optionally, in the embodiment of the present application, the material fixing member includes a left fixing clamp 5 and a right fixing clamp 11. The left fixing clamp 5 is fixed on the left fixing plate 4 at one end of the bottom plate 7, and the right fixing clamp 11 is fixed on the slide table 8 of the slide rail 9.

[0036] Optionally, in the embodiment of the present application, the measuring device further includes:

[0037] A winch 10, the winch 10 is fixed at one end of the bottom plate 7 and is connected to the slide table 8 on the slide rail 9. The slide table 8 is driven to move along the slide rail 9 by rotating the rotary handwheel on the winch 10.

[0038] Specifically, as Figure 1As shown in the figure, rotate the rotary handwheel of the winch 10 on the right side of the device. The steel wire rope pulls the right fixed clamp 11 to drive the sliding table 8 to move. Since the receiving end 12 of the ultrasonic transducer is fixed to the nut seat by screws, and the right fixed clamp 11 is also on the nut seat, the moving distance of the receiving end 12 of the ultrasonic transducer is the same as the stretching length of the resistance wire. Connect the first channel of the low-frequency signal generator 1 to the receiving end 3 of the ultrasonic transducer with a signal wire, convert the sine wave signal emitted by the first channel of the low-frequency signal generator 1 into ultrasonic waves of the same frequency. The ultrasonic waves are transmitted through the air to the transmitting end 12 of the ultrasonic transducer. Connect the transmitting end 12 of the ultrasonic transducer to the first display channel of the oscilloscope 2, so that the sound signal is converted into an electrical signal again and displayed in the first display channel of the oscilloscope 2. Connect the second channel of the low-frequency signal generator 1 to the second display channel of the oscilloscope 2.

[0039] In the embodiment of the present application, both the left fixing plate 4 and the bottom plate 7 are made of smooth and flat materials. The bottom plate 7 is preferably made of steel to prevent the material from deforming due to excessive stretching length and unable to withstand the tensile force. The left fixing plate 4 should be made of a metal with a higher hardness and is fixed by screws. Install the sliding table 8 into the channel of the slide rail 9, install a flat plate and a right fixed clamp 11 above the sliding table 8, and lock the transmitting end of the ultrasonic transducer with a fixed ultrasonic transducer fixing ring. Place the resistance wire to be measured and fix it through the tightening screws in the left fixed clamp 5 and the right fixed clamp 11. Rotate the handwheel of the winch 10 to make the resistance wire in a taut state and lock it. Clip two wire clips on each end of the resistance wire to connect it to the resistance measuring device. Lock the receiving end of the ultrasonic transducer on the movable ultrasonic transducer fixing bracket and ensure that the transmitting end and the receiving end are facing each other and on the same straight line.

[0040] It can be understood that from the initial resistivity formula where L is the length of the resistance wire connected before stretching, which can be directly measured before the experiment starts. S is the cross-sectional area of the resistance wire, and the diameter D of the resistance wire can be measured first by a micrometer. Then from the formula calculate, and then calculate the volume of the resistance wire The resistivity formula is simplified to where ΔR is the change in resistance of the resistance wire after stretching, and ΔL is the change in length of the resistance wire after stretching.

[0041] Also, ΔL = Kλ (K = 0, 1, 2, 3...), where K is the number of stretching times of the resistance wire, and λ is the length of one wavelength in the air.

[0042] The known relationship between wavelength, sound speed, and frequency is: where v is the propagation speed of sound waves in the air at a certain temperature, and f is the optimal operating frequency of the ultrasonic transducer.

[0043] Then calculate the propagation speed of sound waves in the air at a certain temperature:

[0044]

[0045] Among them, V0 = 331.45 m / s is the speed of sound at 0 °C, T0 = 273.15 K, and t is the room temperature, with the unit of °C.

[0046] Substituting the calculation formula, the final calculation formula for the resistivity can be obtained as:

[0047]

[0048] Among them, V is the volume of the resistance wire to be measured, L is the length of the resistance wire to be measured before stretching, T0 is 273.15 Kelvin, V0 is the speed of sound in air at 0 °C, K is the number of stretching times of the resistance wire to be measured, K = 0, 1, 2, 3..., obtained from the change period of the Lissajous figure, ΔR is the change in resistance during the stretching of the resistance wire to be measured, t is the room temperature, and f is the optimal operating frequency of the transmitting end and the receiving end of the ultrasonic transducer.

[0049] In the above formula, the fixed values are the volume V of the resistance wire, the length L of the resistance wire connected before stretching, T0, the speed v0 of sound in air at 0 °C, the variable is the number of stretching times K of the resistance wire, the change in resistance ΔR after stretching the resistance wire, and the room temperature t. Among them, the room temperature can be measured in real time by a thermometer, the number of stretching times K can be obtained from the change period of the Lissajous figure displayed by the oscilloscope, and ΔR can be obtained from the resistance measuring device. After obtaining the values of each parameter, the resistivity of the resistance wire to be measured can be calculated.

[0050] In one embodiment, after installing the instrument, the device needs to be debugged to confirm the optimal operating frequency of the ultrasonic transducer: adjust the output signal so that the amplitude of the low-frequency signal generator 1 is between 8 - 10 Vpp, then carefully adjust the frequency of the output signal, and at the same time observe the change in the amplitude of the received wave. When the amplitude reaches the maximum, this frequency is the frequency that matches the receiving end and the transmitting end of the ultrasonic transducer. After recording this frequency f, change the distance between the receiving end and the transmitting end of the ultrasonic transducer, readjust the frequency to make the amplitude of the received wave reach the maximum again, record the frequency f at this time, and repeat the measurement 5 times in sequence. Take the average value as the optimal operating frequency. Specifically, it is known that the operating frequency f of the used air-coupled ultrasonic transducer is 30 kHz. Under the conditions of one standard atmosphere and 25 °C, the speed of sound v is: From It can be calculated that the length of one wavelength in air is 11.5 mm. Press the display button on the oscilloscope 2 to change the Y-T mode to the X-Y mode (vertical synthesis mode), and the Lissajous figure with a frequency ratio of 1:1 can be observed, as Figure 2As shown, select a suitable pattern as the starting point. When the resistance wire is stretched, since the distance between the transmitting end 3 of the ultrasonic transducer and the receiving end 12 of the ultrasonic transducer changes, the Lissajous pattern displayed on the oscilloscope 2 will also change. When the Lissajous pattern changes by one cycle (from one pattern through a series of changes and back to the original pattern), that is, when the phase difference is 2π, the number of stretching times K of the resistance wire to be measured is 1. Stop rotating the rotary handwheel of the winch 10 and lock it. At this time, the length by which the metal resistance wire is stretched is ΔL = λ = 11.5 mm.

[0051] Optionally, in the embodiment of the present application, the resistance measuring bridge is a double-arm bridge or a single-arm bridge. Among them, the bridge used is an existing one. Taking the double-arm bridge as an example, the double-arm bridge includes: a switch, a combined power supply, a first resistor R1, a second resistor R2, a sensitive galvanometer, and a standard resistor R s ; when no current flows through and the reading of the sensitive galvanometer is 0, the bridge reaches equilibrium. Before stretching the resistance wire to be measured, adjust the standard resistor R s and observe the sensitive galvanometer to make its reading 0. At this time, the resistance value of the resistance wire is R x1 . After stretching the resistance wire to be measured, the resistance value of the resistance wire R x changes, the pointer of the sensitive current meter deflects, and the standard resistor R s is adjusted again to make the pointer of the sensitive current meter point to the zero scale line. The resistance value of the resistance wire measured for the second time is R x2 . Subtract R x2 from R x1 to calculate the resistance change amount ΔR of the resistance wire to be measured during the stretching process.

[0052] Adjust the standard resistor R s in the double-arm bridge, and at the same time observe the deflection of the sensitive galvanometer pointer until it points to the zero scale line, indicating that the bridge reaches equilibrium. Read the value of the standard resistor R s at this time. Then the resistance value R x1 of the resistance wire to be measured at this time is equal to R s . Record R x1 . Rotate the rotary handwheel of the winch 10 and observe the Lissajous pattern displayed on the oscilloscope 2 from Figure 2 (a) through (e) and back to (a). During this process, the phase difference changes by 2π phases, the receiving end 3 of the ultrasonic transducer moves by one wavelength, and the resistance wire is stretched by a length of one wavelength accordingly, that is, ΔL = λ = 11.5 mm. At this time, observe the sensitive galvanometer in the double-arm DC resistance bridge. Since the resistance wire is stretched, its resistance value will surely change, the bridge is no longer in equilibrium, and the pointer no longer points to the zero scale line. At this time, the standard resistor R s, adjust until the pointer of the sensitive galvanometer points to the zero scale line, read the reading of the measuring dial at this time, and calculate and record the resistance value R of the resistance wire at this time according to the above formula x2 , and then use R x2 to subtract R x1 to calculate ΔR x . Continue to slowly rotate the handwheel of the winch 10 and observe the Lissajous figure from Figure 2 (a), through (e) until it changes back to (a) again. Repeat the measurement 5 to 8 groups of data according to the above steps. Substitute the measured several sets of values into the final formula for solving the resistivity respectively, and take the average value of the resistivity ρ calculated multiple times as the final result.

[0053] It can be understood that in the embodiments of the present application, the low-frequency signal generator, oscilloscope, ultrasonic transducer transmitting end, ultrasonic transducer receiving end, and resistance measuring bridge used are all conventional devices, and the functions realized are also inherent functions that the devices can achieve. The present application does not improve the processing methods thereof.

[0054] According to the material resistivity measuring device based on ultrasonic detection technology proposed in the embodiments of the present application, the ultrasonic transducer transmitting end converts the signal according to the sine wave signal generated by the low-frequency signal generator, converts the electrical signal into an ultrasonic signal for transmission; move the ultrasonic transducer receiving end along the slide rail, while stretching the resistance wire to be measured, the ultrasonic transducer receiving end receives the ultrasonic signal transmitted by the ultrasonic transducer transmitting end, and converts the ultrasonic signal into an electrical signal and inputs it into the oscilloscope to display the periodic change process of the Lissajous figure during the stretching process of the resistance wire to be measured. The present application does not need to measure the length change of the resistance wire to be measured, converts the length change into the periodic change of the Lissajous figure, and then calculates the resistance change amount before and after the length change of the resistance wire to be measured according to the periodic change of the Lissajous figure. Combining the change period of the Lissajous figure, the self-parameters of the resistance wire to be measured, and the resistance change amount, calculate the resistivity of the resistance wire to be measured according to the resistivity calculation formula. The present application uses a stable stretching device, observes the display results of various test instruments, records data and calculates to obtain the resistivity of the resistance wire, which is easy to operate and observe and has high measurement accuracy.

[0055] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of this application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or N embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0056] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of this application, "N" means at least two, such as two, three, etc., unless otherwise specifically defined.

Claims

1. A material resistivity measuring device based on ultrasonic detection technology, characterized in that: include: Low frequency signal generator, oscilloscope, ultrasonic transducer transmitting end, material fixing parts, ultrasonic transducer receiving end, resistance measuring bridge; The low-frequency signal generator is used to generate a sine wave signal; The ultrasonic transducer transmitting end is connected to the first port of the low-frequency signal generator, converts the sine wave signal into an ultrasonic signal, and transmits the ultrasonic signal; One end of the material fixing piece is fixed on the bottom plate, and the other end is connected to the receiving end of the ultrasonic transducer, and the material fixing piece is used to fix the two ends of the resistance wire to be measured; The ultrasonic transducer receiving end is arranged on the slide rail of the bottom plate, and receives the ultrasonic signal emitted by the ultrasonic transducer transmitting end while stretching the resistance wire to be measured by moving along the slide rail; The resistance measuring bridge is connected to the resistance wire to be measured, and is used to measure the resistance of the resistance wire to be measured during the stretching process; The first channel of the oscilloscope is connected to the receiving end of the ultrasonic transducer, and the second channel is connected to the second port of the low-frequency signal generator, and is used to display the periodic change process of the Lissajous figure during the stretching process of the resistance wire to be measured. The periodic change of the Lissajous figure reflects the length change of the resistance wire to be measured, and then calculates the resistance change before and after the length change of the resistance wire to be measured. Combined with the change period of the Lissajous figure, the parameters of the resistance wire to be measured and the resistance change, the resistivity of the resistance wire to be measured is calculated according to the resistivity calculation formula.

2. The device according to claim 1, characterized in that The device also includes: A slide table is arranged on the slide rail, and the ultrasonic transducer receiving end is fixed on the slide table.

3. The device according to claim 1 or 2, characterized in that: The material fixing part comprises a left fixing clamp and a right fixing clamp, wherein the left fixing clamp is fixed on a left fixing plate at one end of the bottom plate, and the right fixing clamp is fixed on a slide table of the slide rail.

4. The device according to claim 1, characterized in that The device also includes: A capstan is fixed at one end of the base plate and connected to a slide on the slide rail. The slide is driven to move along the slide rail by rotating a rotating hand wheel on the capstan.

5. The device according to claim 1, characterized in that The resistance measuring bridge is a double-arm bridge or a single-arm bridge.

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