CN211235664U - An air-coupled ultrasonic laminated wood quality detection device - Google Patents
An air-coupled ultrasonic laminated wood quality detection device Download PDFInfo
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Abstract
本实用新型公开了一种空气耦合超声波层积木板质量检测装置，包括单片机、超声波发射电路和超声波接收电路，超声波发射电路包括两路反向方波电路和推挽逆变电路，超声波接收电路包括前置处理电路、前置差分放大电路和二阶反相放大电路。本实用新型为一种以单片机为控制核心的检测装置，装置包括超声波发射电路和超声波接收电路，单片机触发超声波发射电路发射信号，信号在被测物体之间穿透，通过检测超声波回来信号的幅值大小，从而确定被测物体是否存在缺陷；整体电路设计简单但可靠性高，将空气作为耦合剂，超声波探头不需接触工件表面，实现了对木板的质量检测，检测结果准确。
The utility model discloses an air-coupled ultrasonic laminated wood quality detection device, comprising a single-chip microcomputer, an ultrasonic transmitting circuit and an ultrasonic receiving circuit. The ultrasonic transmitting circuit includes two reverse square wave circuits and a push-pull inverter circuit, and the ultrasonic receiving circuit includes Pre-processing circuit, pre-differential amplifier circuit and second-order inverting amplifier circuit. The utility model relates to a detection device with a single-chip microcomputer as the control core. The device comprises an ultrasonic transmitting circuit and an ultrasonic receiving circuit. The single-chip microcomputer triggers the ultrasonic transmitting circuit to transmit a signal, and the signal penetrates between objects to be measured. The overall circuit design is simple but highly reliable, air is used as a couplant, and the ultrasonic probe does not need to touch the surface of the workpiece, which realizes the quality inspection of the wood, and the inspection results are accurate.
Description
技术领域technical field
本实用新型涉及层积木板质量检测技术领域，具体涉及一种空气耦合超声波层积木板质量检测装置。The utility model relates to the technical field of quality detection of laminated wooden boards, in particular to an air-coupled ultrasonic laminated wooden board quality detection device.
背景技术Background technique
传统的木材检测方法在检测时都会对木材造成不同程度的破坏，需要将木材取样本记录大小、形状等，通过这些方式不仅造成木材缺棱、锯口等加工缺陷，还会影响木材的使用，造成木材资源的浪费。常规的超声波木材无损检测技术通常需要在被检测木材两侧粘合耦合剂，降低超声波在空气中的衰减。但是耦合剂一般为流体，会污染被检测木材的表面，严重情况可能会渗入木材，对木材造成一定的破坏。同时，一旦环境温度发生变化，耦合条件也随之变化，那么对试验结果也会产生误差，影响缺陷的判断。The traditional wood detection methods will cause different degrees of damage to the wood during detection. It is necessary to take samples of the wood to record the size, shape, etc. These methods not only cause processing defects such as missing edges and saw cuts, but also affect the use of wood. waste of wood resources. Conventional ultrasonic wood non-destructive testing technology usually requires bonding couplant on both sides of the tested wood to reduce the attenuation of ultrasonic waves in the air. However, the coupling agent is generally a fluid, which will contaminate the surface of the tested wood. In severe cases, it may penetrate into the wood and cause certain damage to the wood. At the same time, once the ambient temperature changes, the coupling conditions also change, which will cause errors in the test results and affect the judgment of defects.
在航空航天、医学、食品等领域，许多检测工件不能接触耦合剂，在某些高温条件下，空气耦合超声波检测更具有竞争力。近些年来，随着空气耦合超声波技术的不断发展，已经在航天固体燃料的检测、空气耦合超声测距、锂离子电池电解液气泡的检测等领域进行应用，因此设计一种空气耦合式超声波无损检测电路，将空气作为耦合剂，超声波探头不接触工件表面，从而实现对层积木板的质量检测是目前的发展趋势，进而真正意义上实现了无损检测，弥补接触式超声波检测的一些不足。In the fields of aerospace, medicine, food, etc., many inspection workpieces cannot contact the couplant, and under certain high temperature conditions, air-coupled ultrasonic inspection is more competitive. In recent years, with the continuous development of air-coupled ultrasonic technology, it has been applied in aerospace solid fuel detection, air-coupled ultrasonic ranging, and lithium-ion battery electrolyte bubble detection. Therefore, an air-coupled ultrasonic nondestructive The detection circuit uses air as a couplant, and the ultrasonic probe does not contact the surface of the workpiece, so as to realize the quality inspection of laminated wood.
实用新型内容Utility model content
本实用新型所要解决的技术问题是针对上述现有技术的不足提供一种空气耦合超声波层积木板质量检测装置，本空气耦合超声波层积木板质量检测装置为一种以单片机为控制核心的检测装置，装置包括超声波发射电路和超声波接收电路，单片机触发超声波发射电路发射信号，信号在被测物体之间穿透，通过检测超声波回来信号的幅值大小，从而确定被测物体是否存在缺陷；整体电路设计简单但可靠性高，将空气作为耦合剂，超声波探头不需接触工件表面，实现了对木板的质量检测，检测结果准确。The technical problem to be solved by this utility model is to provide an air-coupled ultrasonic laminated wood board quality detection device for the shortcomings of the above-mentioned prior art. The air-coupled ultrasonic laminated wood board quality detection device is a detection device with a single-chip microcomputer as the control core , the device includes an ultrasonic transmitting circuit and an ultrasonic receiving circuit. The single-chip microcomputer triggers the ultrasonic transmitting circuit to transmit a signal, and the signal penetrates between the measured objects. By detecting the amplitude of the ultrasonic signal returned, it is determined whether the measured object has defects; the overall circuit The design is simple but the reliability is high. The air is used as the coupling agent, and the ultrasonic probe does not need to contact the surface of the workpiece, which realizes the quality inspection of the wood board, and the inspection result is accurate.
为实现上述技术目的，本实用新型采取的技术方案为：In order to realize the above-mentioned technical purpose, the technical scheme adopted by the present utility model is:
一种空气耦合超声波层积木板质量检测装置，包括单片机、超声波发射电路和超声波接收电路，所述超声波发射电路包括两路反向方波电路和推挽逆变电路，所述超声波接收电路包括前置处理电路、前置差分放大电路和二阶反相放大电路，所述单片机同时与两路反向方波电路和推挽逆变电路连接，所述两路反向方波电路与推挽逆变电路连接，所述前置处理电路与前置差分放大电路连接，所述前置差分放大电路与二阶反相放大电路连接，所述二阶反相放大电路与单片机连接。An air-coupled ultrasonic laminated wood quality detection device, comprising a single-chip microcomputer, an ultrasonic transmitting circuit and an ultrasonic receiving circuit, the ultrasonic transmitting circuit includes two reverse square wave circuits and a push-pull inverter circuit, and the ultrasonic receiving circuit includes a front A processing circuit, a pre-differential amplifying circuit and a second-order inverting amplifying circuit are provided, and the single-chip microcomputer is simultaneously connected with two reverse square wave circuits and a push-pull inverter circuit, and the two reverse square wave circuits are connected with a push-pull inverter The variable circuit is connected, the preprocessing circuit is connected with the pre-differential amplifying circuit, the pre-differential amplifying circuit is connected with the second-order inverting amplifying circuit, and the second-order inverting amplifying circuit is connected with the single-chip microcomputer.
作为本实用新型进一步改进的技术方案，所述单片机采用芯片STM32F103VET6。As a further improved technical solution of the present invention, the single-chip microcomputer adopts the chip STM32F103VET6.
作为本实用新型进一步改进的技术方案，所述两路反向方波电路包括非门74HC04，所述单片机的PB1引脚与非门74HC04的引脚1连接，所述非门74HC04的引脚7连接地线，非门74HC04的引脚14连接5V电源，所述非门74HC04的引脚2与推挽逆变电路连接。As a further improved technical solution of the present invention, the two-way reverse square wave circuit includes a NOT gate 74HC04, the PB1 pin of the single-chip microcomputer is connected to the pin 1 of the NOT gate 74HC04, and the
作为本实用新型进一步改进的技术方案，所述推挽逆变电路包括芯片MC34151、电阻R3、电阻R4、电阻R5、电阻R6、MOS管Q1、MOS管Q2、电容C1、电容C2、变压器T1和超声波发射装置，所述芯片MC34151的引脚2与非门74HC04的引脚2连接，所述芯片MC34151的引脚4与单片机的PB1引脚连接，所述芯片MC34151的引脚3连接地线，所述芯片MC34151的引脚6连接12V电源，所述芯片MC34151的引脚7连接电阻R3，所述电阻R3的另一端与MOS管Q1的栅极连接，所述MOS管Q1的漏极同时连接电容C1和电阻R5，所述MOS管Q1的源极接地，所述电阻R5的另一端与变压器原边的一端连接，所述芯片MC34151的引脚5连接电阻R4，所述电阻R4的另一端与MOS管Q2的栅极连接，所述MOS管Q2的漏极同时连接电容C2和电阻R6，所述MOS管Q2的源极接地，所述电阻R6的另一端与变压器原边的另一端连接，所述变压器的中心抽头端连接12V电源，所述变压器副边的两端与超声波发射装置连接。As a further improved technical solution of the present invention, the push-pull inverter circuit includes a chip MC34151, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a MOS transistor Q1, a MOS transistor Q2, a capacitor C1, a capacitor C2, a transformer T1 and Ultrasonic transmitting device, the
作为本实用新型进一步改进的技术方案，所述前置处理电路包括超声波接收装置、电阻R7、电容C3、电容C4、电阻R8、电阻R9、二极管D1和二极管D2，所述超声波接收装置的一端同时与电阻R7和电容C3的一端连接，所述超声波接收装置的另一端同时与电阻R7和电容C4的一端连接，所述电容C3的另一端同时与电阻R8的一端和前置差分放大电路连接，所述电阻R8的另一端连接地线，所述电容C4的另一端同时与电阻R9的一端和前置差分放大电路连接，所述电阻R9的另一端连接地线，所述二极管D1的正极和二极管D2的负极均与电容C3的一端连接，所述二极管D1的负极和二极管D2的正极均与电容C4的一端连接。As a further improved technical solution of the present invention, the preprocessing circuit includes an ultrasonic receiving device, a resistor R7, a capacitor C3, a capacitor C4, a resistor R8, a resistor R9, a diode D1 and a diode D2, and one end of the ultrasonic receiving device is simultaneously It is connected with one end of the resistor R7 and the capacitor C3, the other end of the ultrasonic receiving device is connected with one end of the resistor R7 and the capacitor C4 at the same time, and the other end of the capacitor C3 is connected with one end of the resistor R8 and the pre-differential amplifier circuit at the same time, The other end of the resistor R8 is connected to the ground wire, the other end of the capacitor C4 is connected to one end of the resistor R9 and the pre-differential amplifier circuit at the same time, the other end of the resistor R9 is connected to the ground wire, the anode of the diode D1 and the The cathode of the diode D2 is connected to one end of the capacitor C3, and the cathode of the diode D1 and the anode of the diode D2 are both connected to one end of the capacitor C4.
作为本实用新型进一步改进的技术方案，所述前置差分放大电路包括电阻R10、电阻R11、滑动变阻器R12和放大器AD620，所述电阻R10的一端与电容C3的一端连接，所述电阻R10的另一端与放大器AD620的引脚2连接，所述电阻R11的一端与电容C4的一端连接，所述电阻R11的另一端与放大器AD620的引脚3连接，所述放大器AD620的引脚1通过滑动变阻器R12与放大器AD620的引脚8连接，所述放大器AD620的引脚5连接地线，所述放大器AD620的引脚4连接-12V电源，所述放大器AD620的引脚7连接+12V电源，所述放大器AD620的引脚6与二阶反相放大电路连接。As a further improved technical solution of the present invention, the pre-differential amplifier circuit includes a resistor R10, a resistor R11, a sliding varistor R12 and an amplifier AD620, one end of the resistor R10 is connected to one end of the capacitor C3, and the other end of the resistor R10 is connected One end is connected to the
作为本实用新型进一步改进的技术方案，所述二阶反相放大电路包括电容C5、电阻R13、滑动变阻器R14、电阻R15、电阻R16、滑动变阻器R17、电阻R18、第一运放芯片OP37和第二运放芯片OP37，所述电容C5的一端与放大器AD620的引脚6连接，电容C5的另一端与电阻R13的一端连接，电阻R13的另一端同时与滑动变阻器R14和第一运放芯片OP37的引脚2连接，第一运放芯片OP37的引脚3通过电阻R15连接地线，第一运放芯片OP37的引脚4连接-12V电源，第一运放芯片OP37的引脚7连接+12V电源，第一运放芯片OP37的引脚6与滑动变阻器R14的另一端连接且第一运放芯片OP37的引脚6通过电阻R16与第二运放芯片OP37的引脚2连接，第二运放芯片OP37的引脚2通过滑动变阻器R17与第二运放芯片OP37的引脚6连接，第二运放芯片OP37的引脚3通过电阻R18连接地线，第二运放芯片OP37的引脚4连接-12V电源，第二运放芯片OP37的引脚7连接+12V电源，第二运放芯片OP37的引脚6与单片机的PA2引脚连接。As a further improved technical solution of the present invention, the second-order inverting amplifier circuit includes a capacitor C5, a resistor R13, a sliding rheostat R14, a resistor R15, a resistor R16, a sliding rheostat R17, a resistor R18, a first operational amplifier chip OP37 and a second Two operational amplifier chips OP37, one end of the capacitor C5 is connected to
本实用新型的有益效果为：本实用新型为一种以51单片机微处理器为控制核心的检测装置，装置由超声波发射电路和超声波接收电路组成。单片机触发超声波电路发射信号，信号在被测木板之间穿透，通过超声波接收电路接收回来的信号，并通过单片机的PA2引脚检测超声波回来信号的幅值大小，从而确定被测木板是否存在缺陷，检测结果准确。整体电路设计简单但可靠性高，将空气作为耦合剂，超声波探头不需接触工件表面，实现了对层积木板的无损检测，弥补接触式超声波检测的一些不足。The beneficial effects of the utility model are as follows: the utility model is a detection device with a 51 single-chip microprocessor as the control core, and the device is composed of an ultrasonic transmitting circuit and an ultrasonic receiving circuit. The single-chip microcomputer triggers the ultrasonic circuit to transmit the signal, the signal penetrates between the boards under test, the signal received by the ultrasonic receiving circuit, and the amplitude of the returned ultrasonic signal is detected through the PA2 pin of the single-chip microcomputer, so as to determine whether the board under test has defects , the detection result is accurate. The overall circuit design is simple but has high reliability. Air is used as a couplant, and the ultrasonic probe does not need to contact the surface of the workpiece.
附图说明Description of drawings
图1为本实施例两路反向方波电路示意图。FIG. 1 is a schematic diagram of a two-way reverse square wave circuit of this embodiment.
图2为本实施例推挽逆变电路示意图。FIG. 2 is a schematic diagram of a push-pull inverter circuit of this embodiment.
图3为本实施例前置处理电路示意图。FIG. 3 is a schematic diagram of a preprocessing circuit of this embodiment.
图4为本实施例前置差分放大电路示意图。FIG. 4 is a schematic diagram of a pre-differential amplifier circuit of this embodiment.
图5为本实施例二阶反相放大电路示意图。FIG. 5 is a schematic diagram of the second-order inverting amplifying circuit of this embodiment.
具体实施方式Detailed ways
下面根据图1至图5对本实用新型的具体实施方式作出进一步说明：Below according to Fig. 1 to Fig. 5, the specific embodiment of the present utility model is further described:
一种空气耦合超声波层积木板质量检测装置，包括单片机、超声波发射电路和超声波接收电路，所述超声波发射电路包括两路反向方波电路和推挽逆变电路，所述超声波接收电路包括前置处理电路、前置差分放大电路和二阶反相放大电路，所述单片机同时与两路反向方波电路和推挽逆变电路连接，所述两路反向方波电路与推挽逆变电路连接，所述前置处理电路与前置差分放大电路连接，所述前置差分放大电路与二阶反相放大电路连接，所述二阶反相放大电路与单片机连接。An air-coupled ultrasonic laminated wood quality detection device, comprising a single-chip microcomputer, an ultrasonic transmitting circuit and an ultrasonic receiving circuit, the ultrasonic transmitting circuit includes two reverse square wave circuits and a push-pull inverter circuit, and the ultrasonic receiving circuit includes a front A processing circuit, a pre-differential amplifying circuit and a second-order inverting amplifying circuit are provided, and the single-chip microcomputer is simultaneously connected with two reverse square wave circuits and a push-pull inverter circuit, and the two reverse square wave circuits are connected with a push-pull inverter The variable circuit is connected, the preprocessing circuit is connected with the pre-differential amplifying circuit, the pre-differential amplifying circuit is connected with the second-order inverting amplifying circuit, and the second-order inverting amplifying circuit is connected with the single-chip microcomputer.
本实施例中，所述单片机采用芯片STM32F103VET6，是基于ARM Cortex- M3的32位系统单片机，这款芯片主频工作速度达72MHz，速度快，效率高，同时板载资源十分丰富，内部拥有高速存储器FLASH和EEPROM可供存储数据。芯片的外设资源包括，AD采集、USART串口、TIMER定时器等，还包含标准的通信接口：包含两个I2C 接口、三个SPI 、两个I2S 、一个SDIO 、五个USART 、一个USB 以及一个CAN。STM32F103x内置的ARM兼容多种开发工具，丰富的库函数使得程序更易移植，简单方便，易于理解。内部FLASH可在线编程，处理器功耗低，运行速度快，是嵌入式领域中不可或缺的一部分。In this embodiment, the single-chip microcomputer adopts the chip STM32F103VET6, which is a 32-bit system single-chip microcomputer based on ARM Cortex-M3. The main frequency of this chip is up to 72MHz, with high speed and high efficiency. Memory FLASH and EEPROM are available for storing data. The peripheral resources of the chip include AD acquisition, USART serial port, TIMER timer, etc., as well as standard communication interfaces: including two I2C interfaces, three SPIs, two I2Ss, one SDIO, five USARTs, One USB and one CAN. The built-in ARM of STM32F103x is compatible with a variety of development tools, and the rich library functions make the program easier to transplant, simple and convenient, and easy to understand. The internal FLASH can be programmed online, the processor has low power consumption and fast running speed, which is an indispensable part in the embedded field.
本实施例中，如图1所示，所述两路反向方波电路包括非门74HC04，所述单片机的PB1引脚与非门74HC04的引脚1连接，所述非门74HC04的引脚7连接地线，非门74HC04的引脚14连接5V电源，所述非门74HC04的引脚2与推挽逆变电路连接。In this embodiment, as shown in FIG. 1 , the two-way reverse square wave circuit includes a NOT gate 74HC04, the PB1 pin of the single-chip microcomputer is connected to the pin 1 of the NOT gate 74HC04, and the pin of the NOT gate 74HC04 is connected. 7 is connected to the ground wire, the
由于单片机只能产生一路脉冲方波，所以将一路信号接非门74HC04，产生反相方波信号。74HC04是一个含有6组非门的高速反相器，本实施例使用了其中一组反相器，将信号从1脚输入，2脚输出，芯片的7脚接地，14脚接＋5V电源。这样就产生了两路反相方波信号（即A1和A2两路）。Since the single-chip microcomputer can only generate one pulse square wave, connect one signal to the NOT gate 74HC04 to generate an inverse square wave signal. 74HC04 is a high-speed inverter with 6 sets of NOT gates. This embodiment uses one set of inverters to input signals from pin 1 and output from
本实施例中，如图2所示，所述推挽逆变电路包括芯片MC34151、电阻R3、电阻R4、电阻R5、电阻R6、MOS管Q1、MOS管Q2、电容C1、电容C2、变压器T1和超声波发射装置，所述芯片MC34151的引脚2与非门74HC04的引脚2连接，所述芯片MC34151的引脚4与单片机的PB1引脚连接，所述芯片MC34151的引脚3连接地线，所述芯片MC34151的引脚6连接+12V电源，所述芯片MC34151的引脚7连接电阻R3，所述电阻R3的另一端与MOS管Q1的栅极连接，所述MOS管Q1的漏极同时连接电容C1和电阻R5，所述MOS管Q1的源极接地，所述电阻R5的另一端与变压器原边的一端连接，所述芯片MC34151的引脚5连接电阻R4，所述电阻R4的另一端与MOS管Q2的栅极连接，所述MOS管Q2的漏极同时连接电容C2和电阻R6，所述MOS管Q2的源极接地，所述电阻R6的另一端与变压器原边的另一端连接，所述变压器的中心抽头端连接+12V电源，所述变压器副边的两端与超声波发射装置（即超声波发射探头）连接。In this embodiment, as shown in FIG. 2 , the push-pull inverter circuit includes a chip MC34151, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a MOS transistor Q1, a MOS transistor Q2, a capacitor C1, a capacitor C2, and a transformer T1 And the ultrasonic transmitting device, the
由于超声波探头需要一定功率的高频高压脉冲信号激励，因此由单片机产生的高频小信号必须经过高频脉冲变压器来进行电压升压，功率放大。根据电路拓扑结构，由MOSFET构成的逆变器主要包括三种类型：半桥、全桥和推挽式。在推挽电路中，由于MOS管的源极接地，所以不需要在两组电路之间再绝缘，电路结构简单。超声波探头的激励电压需要在400-600V之间，所以设计合适的推挽逆变电路用于本实施例。Since the ultrasonic probe needs a certain power of high-frequency high-voltage pulse signal excitation, the high-frequency small signal generated by the single-chip microcomputer must go through a high-frequency pulse transformer to boost the voltage and amplify the power. According to the circuit topology, inverters composed of MOSFETs mainly include three types: half-bridge, full-bridge and push-pull. In the push-pull circuit, since the source of the MOS tube is grounded, there is no need to re-insulate between the two sets of circuits, and the circuit structure is simple. The excitation voltage of the ultrasonic probe needs to be between 400-600V, so an appropriate push-pull inverter circuit is designed for this embodiment.
Q1、Q2 两个MOS管在两个方波的作用下使变压器初级中心端与地交替导通。当MOS管导通时，漏极和源极之间电阻很小，相当于短路，而源极接地，所以漏极电压被拉低，为低电平。当MOS管截止时，漏极和源极之间电阻非常大，相当于开路，因此漏极电压等于变压器中心抽头端的电压，为高电平。所以在推挽模式下，两个MOS管交替导通，在变压器初级就形成了极性交替变化的方波电压。Under the action of two square waves, the two MOS tubes Q1 and Q2 make the primary center end of the transformer and the ground alternately conduct. When the MOS tube is turned on, the resistance between the drain and the source is very small, which is equivalent to a short circuit, and the source is grounded, so the drain voltage is pulled down to a low level. When the MOS tube is turned off, the resistance between the drain and the source is very large, which is equivalent to an open circuit, so the drain voltage is equal to the voltage at the center tap of the transformer, which is a high level. Therefore, in the push-pull mode, the two MOS tubes are turned on alternately, and a square wave voltage with alternating polarities is formed at the primary stage of the transformer.
在本实施例中，Q1、Q2 两个MOS管选择了由IR公司生产的N沟道型IRF840，这款MOS管最大工作电压可达500V,导通时间短，属于电压型驱动器件，具有输入阻抗高、速度快、驱动电路简单等优点。In this embodiment, the two MOS transistors Q1 and Q2 are N-channel type IRF840 produced by IR Company. The maximum working voltage of this MOS transistor can reach 500V, and the on-time is short. It is a voltage-type driving device with input It has the advantages of high impedance, fast speed and simple driving circuit.
MOS管的驱动芯片选择了双反转高压高速功率驱动器MC34151，该器件采用了高度集成的电平转换技术，逻辑输入可接受3.3V与5V电平，使得逻辑电路对功率器件的控制更为简单化，也简化了驱动电路的结构，提高了可靠性。芯片的逻辑供电电源范围在5~20V，结构简单，使用方便，减少了系统的供电电源个数，降低了成本，该所以本实施例选用了该芯片作为MOS管的驱动芯片。MC34151的2脚与4脚接输入信号，7脚与5脚分别对应其输出信号，6脚接+12V电源，3脚接地。The driver chip of the MOS tube selects the double-inversion high-voltage high-speed power driver MC34151. The device adopts a highly integrated level conversion technology. The logic input can accept 3.3V and 5V levels, which makes the logic circuit control of the power device simpler. It also simplifies the structure of the drive circuit and improves the reliability. The logic power supply range of the chip is 5~20V, the structure is simple, the use is convenient, the number of power supplies of the system is reduced, and the cost is reduced. The 2 feet and 4 feet of MC34151 are connected to the input signal, the 7 feet and 5 feet are respectively corresponding to its output signal, the 6 feet are connected to the +12V power supply, and the 3 feet are grounded.
本实施例选用的超声波探头需要40kHz的高频高压脉冲激励，为了提高变压器性能，减小变压器工作时的损耗，变压器T1的磁芯应选择高饱和磁感应强度、高导磁率、低剩磁感应、损耗小以及温度稳定性好的材料作磁芯，即选用锰锌铁氧体磁芯，磁芯结构为EE型。The ultrasonic probe selected in this embodiment needs high-frequency high-voltage pulse excitation of 40 kHz. In order to improve the performance of the transformer and reduce the loss during operation of the transformer, the magnetic core of the transformer T1 should be selected with high saturation magnetic induction intensity, high magnetic permeability, low residual magnetic induction and loss. The material with small size and good temperature stability is used as the magnetic core, that is, the manganese-zinc ferrite magnetic core is selected, and the magnetic core structure is EE type.
本实施例中，如图3所示，所述前置处理电路包括超声波接收装置（即超声波接收探头）、电阻R7、电容C3、电容C4、电阻R8、电阻R9、二极管D1和二极管D2，所述超声波接收装置的一端同时与电阻R7和电容C3的一端连接，所述超声波接收装置的另一端同时与电阻R7和电容C4的一端连接，所述电容C3的另一端同时与电阻R8的一端和前置差分放大电路连接，所述电阻R8的另一端连接地线，所述电容C4的另一端同时与电阻R9的一端和前置差分放大电路连接，所述电阻R9的另一端连接地线，所述二极管D1的正极和二极管D2的负极均与电容C3的一端连接，所述二极管D1的负极和二极管D2的正极均与电容C4的一端连接。In this embodiment, as shown in FIG. 3 , the preprocessing circuit includes an ultrasonic receiving device (ie, an ultrasonic receiving probe), a resistor R7, a capacitor C3, a capacitor C4, a resistor R8, a resistor R9, a diode D1 and a diode D2, so One end of the ultrasonic receiving device is simultaneously connected with one end of the resistor R7 and the capacitor C3, the other end of the ultrasonic receiving device is simultaneously connected with one end of the resistor R7 and the capacitor C4, and the other end of the capacitor C3 is simultaneously connected with one end of the resistor R8 and one end of the capacitor C4. The pre-differential amplifier circuit is connected, the other end of the resistor R8 is connected to the ground wire, the other end of the capacitor C4 is connected to one end of the resistor R9 and the pre-differential amplifier circuit at the same time, and the other end of the resistor R9 is connected to the ground wire, The anode of the diode D1 and the cathode of the diode D2 are both connected to one end of the capacitor C3, and the cathode of the diode D1 and the anode of the diode D2 are both connected to one end of the capacitor C4.
此电路为超声波接收电路的前置处理信号，其主要目的是消除直流偏置和限幅。超声波信号在经过了“空气—木板—空气”两次介质转换后，其透射信号中通常带有直流小信号，为了避免这些信号对超声波后续放大电路的影响，所以在前置处理电路中加入两个滤直电容C3、C4。限幅电路由两个反向二极管D1、D2并联接地而成，因为超声波透射信号很微弱，在毫伏级，不能使二极管导通，因此会直接流入后续的放大电路。This circuit is the pre-processing signal of the ultrasonic receiving circuit, and its main purpose is to eliminate the DC offset and limit. After the ultrasonic signal has undergone two medium conversions of "air-board-air", the transmission signal usually contains small DC signals. In order to avoid the influence of these signals on the subsequent ultrasonic amplification circuit, two A filter capacitor C3, C4. The limiter circuit is made up of two reverse diodes D1 and D2 connected in parallel. Because the ultrasonic transmission signal is very weak, at the millivolt level, the diode cannot be turned on, so it will flow directly into the subsequent amplifier circuit.
本实施例中，如图4所示，所述前置差分放大电路包括电阻R10、电阻R11、滑动变阻器R12和放大器AD620，所述电阻R10的一端与电容C3的一端连接，所述电阻R10的另一端与放大器AD620的引脚2连接，所述电阻R11的一端与电容C4的一端连接，所述电阻R11的另一端与放大器AD620的引脚3连接，所述放大器AD620的引脚1通过滑动变阻器R12与放大器AD620的引脚8连接，所述放大器AD620的引脚5连接地线，所述放大器AD620的引脚4连接-12V电源，所述放大器AD620的引脚7连接+12V电源，所述放大器AD620的引脚6与二阶反相放大电路连接。In this embodiment, as shown in FIG. 4 , the pre-differential amplifying circuit includes a resistor R10, a resistor R11, a sliding varistor R12 and an amplifier AD620. One end of the resistor R10 is connected to one end of the capacitor C3, and the resistor R10 is connected to one end of the capacitor C3. The other end is connected to the
超声波在经过两次介质转换到达超声波接收探头后，透射信号幅值非常微弱，一般只有十几毫伏甚至几毫伏，所以必须经过前置放大器来放大信号。由于超声波接收探头输出电阻非常大，因此第一级放大电路必须具有足够大的输入阻抗。本实施例选用了高精度、高输入阻抗、高共模抑制比、低噪声的仪表放大器AD620作为前置放大器。After the ultrasonic wave reaches the ultrasonic receiving probe through two medium conversions, the amplitude of the transmitted signal is very weak, generally only ten millivolts or even a few millivolts, so the signal must be amplified by a preamplifier. Since the output resistance of the ultrasonic receiving probe is very large, the first-stage amplifying circuit must have a large enough input impedance. In this embodiment, an instrumentation amplifier AD620 with high precision, high input impedance, high common mode rejection ratio and low noise is selected as the preamplifier.
空气耦合式超声波无损检测在实际应用过程中，由于被检测材料的厚度不一、材质不一，所以使得超声波透射信号的大小存在较大差异。当材质与空气声阻抗越不匹配，激励电压小，材料厚度大时，接收到的透射信号幅值也就越小。相反的，当材质与空气声阻抗匹配程度高，激励电压大，材料厚度小时，接收到的透射信号幅值也就越大。所以，为了提高本检测装置的检测范围以及装置的适应性，就需要设计一种既要满足超声波空气耦合检测放大倍数要求又不会因为信号过大而饱和的可控增益放大电路。In the actual application process of air-coupled ultrasonic nondestructive testing, due to the different thicknesses and materials of the tested materials, there is a large difference in the size of the ultrasonic transmission signal. When the material does not match the acoustic impedance of the air, the excitation voltage is small, and the material thickness is large, the amplitude of the received transmission signal is also smaller. On the contrary, when the material and air acoustic impedance match is high, the excitation voltage is large, and the thickness of the material is small, the amplitude of the received transmission signal is also larger. Therefore, in order to improve the detection range of the detection device and the adaptability of the device, it is necessary to design a controllable gain amplifying circuit that not only meets the requirements of ultrasonic air coupling detection amplification, but also does not saturate due to excessive signal.
比例放大电路分为两种，一种是输入电阻很高的同相比例放大电路，在理想状态下可视为无穷大。另一种是输入电阻很小的反相比例放大电路。经过第一级AD620差分放大后，超声波透射信号的阻抗已经很小，所以本实施例选用反相比例放大电路，具体结构如图5所示。There are two kinds of proportional amplifier circuits. One is the same-phase proportional amplifier circuit with high input resistance, which can be regarded as infinite in ideal state. The other is an inverse proportional amplifier circuit with a small input resistance. After the first-stage AD620 differential amplification, the impedance of the ultrasonic transmission signal is already very small, so this embodiment selects an inverse proportional amplifier circuit, and the specific structure is shown in Figure 5.
本实施例中，如图5所示，二阶反相放大电路包括电容C5、电阻R13、滑动变阻器R14、电阻R15、电阻R16、滑动变阻器R17、电阻R18、第一运放芯片OP37和第二运放芯片OP37，所述电容C5的一端与放大器AD620的引脚6连接，电容C5的另一端与电阻R13的一端连接，电阻R13的另一端同时与滑动变阻器R14和第一运放芯片OP37的引脚2连接，第一运放芯片OP37的引脚3通过电阻R15连接地线，第一运放芯片OP37的引脚4连接-12V电源，第一运放芯片OP37的引脚7连接+12V电源，第一运放芯片OP37的引脚6与滑动变阻器R14的另一端连接且第一运放芯片OP37的引脚6通过电阻R16与第二运放芯片OP37的引脚2连接，第二运放芯片OP37的引脚2通过滑动变阻器R17与第二运放芯片OP37的引脚6连接，第二运放芯片OP37的引脚3通过电阻R18连接地线，第二运放芯片OP37的引脚4连接-12V电源，第二运放芯片OP37的引脚7连接+12V电源，第二运放芯片OP37的引脚6与单片机的PA2引脚连接。In this embodiment, as shown in FIG. 5 , the second-order inverting amplifier circuit includes a capacitor C5, a resistor R13, a sliding rheostat R14, a resistor R15, a resistor R16, a sliding rheostat R17, a resistor R18, a first operational amplifier chip OP37 and a second The operational amplifier chip OP37, one end of the capacitor C5 is connected to the
本实施例以51单片机微处理器为控制核心的检测系统，系统由超声波发射电路和超声波接收电路组成。单片机触发超声波电路发射信号，信号在被测木板之间穿透，通过超声波接收电路接收回来的信号，并通过单片机的PA2引脚检测超声波回来信号的幅值大小，从而确定被测木板是否存在缺陷。In this embodiment, the detection system with 51 single-chip microprocessor as the control core is composed of an ultrasonic transmitting circuit and an ultrasonic receiving circuit. The single-chip microcomputer triggers the ultrasonic circuit to transmit the signal, the signal penetrates between the boards under test, the signal received by the ultrasonic receiving circuit, and the amplitude of the returned ultrasonic signal is detected through the PA2 pin of the single-chip microcomputer, so as to determine whether the board under test has defects .
本实用新型的保护范围包括但不限于以上实施方式，本实用新型的保护范围以权利要求书为准，任何对本技术做出的本领域的技术人员容易想到的替换、变形、改进均落入本实用新型的保护范围。The protection scope of the present invention includes, but is not limited to, the above embodiments. The protection scope of the present invention is subject to the claims, and any replacement, deformation, and improvement that are easily thought of by those skilled in the art made by the present technology all fall into the scope of the present invention. The scope of protection of the utility model.
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|---|---|---|---|---|
| CN116846372A (en) * | 2023-07-04 | 2023-10-03 | 广州联航科电气机械有限公司 | Alternating-current charging pile control guide PWM (pulse-Width modulation) generation and detection circuit |
| CN116846372B (en) * | 2023-07-04 | 2024-06-11 | 广州联航科电气机械有限公司 | Alternating-current charging pile control guide PWM (pulse-Width modulation) generation and detection circuit |
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