CN211235664U

CN211235664U - Air coupling ultrasonic wave lamination wood board quality detection device

Info

Publication number: CN211235664U
Application number: CN201922382452.1U
Authority: CN
Inventors: 朱昊; 赵心悦; 王正
Original assignee: Nanjing Forestry University
Current assignee: Nanjing Forestry University
Priority date: 2019-12-26
Filing date: 2019-12-26
Publication date: 2020-08-11
Anticipated expiration: 2029-12-26

Abstract

The utility model discloses an air coupling ultrasonic wave lamination wood board quality detection device, including singlechip, ultrasonic emission circuit and ultrasonic receiving circuit, ultrasonic emission circuit includes two way reverse square wave circuit and push-pull inverter circuit, and ultrasonic receiving circuit includes leading processing circuit, leading difference amplifier circuit and second order inverting amplifier circuit. The utility model relates to a detection device with singlechip as control core, the device includes ultrasonic emission circuit and ultrasonic receiving circuit, and the singlechip triggers ultrasonic emission circuit transmission signal, and the signal pierces through between the testee, comes back the amplitude size of signal through detecting the ultrasonic wave to confirm whether there is the defect in the testee; the whole circuit is simple in design and high in reliability, air is used as a coupling agent, an ultrasonic probe does not need to contact the surface of a workpiece, the quality of the wood board is detected, and the detection result is accurate.

Description

Air coupling ultrasonic wave lamination wood board quality detection device

Technical Field

The utility model relates to a laminated wood quality testing technique field, concretely relates to air coupling ultrasonic wave lamination wood board quality detection device.

Background

The traditional wood detection method can damage wood in different degrees during detection, the size, the shape and the like of a sample of the wood are required to be recorded, and the defects of edge missing, saw cut and the like of the wood are caused by the modes, the use of the wood is influenced, and the waste of wood resources is caused. The conventional ultrasonic wood nondestructive testing technology generally needs to adhere coupling agents on two sides of the tested wood, so that the attenuation of ultrasonic waves in air is reduced. However, the coupling agent is generally a fluid, and can contaminate the surface of the wood to be detected, and in severe cases, the coupling agent can penetrate into the wood to cause certain damage to the wood. Meanwhile, once the environmental temperature changes, the coupling condition also changes, so that errors are generated on the test result, and the judgment of defects is influenced.

In the fields of aerospace, medicine, food and the like, a plurality of detection workpieces cannot contact the coupling agent, and air coupling ultrasonic detection is more competitive under certain high-temperature conditions. In recent years, with the continuous development of air coupling ultrasonic technology, the air coupling ultrasonic nondestructive testing circuit is applied to the fields of aerospace solid fuel detection, air coupling ultrasonic distance measurement, lithium ion battery electrolyte bubble detection and the like, so that the air coupling type ultrasonic nondestructive testing circuit is designed, air is used as a coupling agent, an ultrasonic probe is not in contact with the surface of a workpiece, the quality detection of laminated wood boards is realized according to the current development trend, the nondestructive testing is realized in a true sense, and some defects of contact type ultrasonic testing are overcome.

SUMMERY OF THE UTILITY MODEL

The utility model aims to solve the technical problem that the shortcoming of above-mentioned prior art provides an air coupling ultrasonic wave lamination wood board quality detection device, this air coupling ultrasonic wave lamination wood board quality detection device is a detection device who uses the singlechip as control core, and the device includes ultrasonic emission circuit and ultrasonic wave receiving circuit, and the singlechip triggers ultrasonic emission circuit transmission signal, and the signal pierces through between the measured object, returns the amplitude size of signal through detecting the ultrasonic wave to confirm whether there is the defect in the measured object; the whole circuit is simple in design and high in reliability, air is used as a coupling agent, an ultrasonic probe does not need to contact the surface of a workpiece, the quality of the wood board is detected, and the detection result is accurate.

In order to realize the technical purpose, the utility model discloses the technical scheme who takes does:

the utility model provides an air coupling ultrasonic wave lamination building block quality detection device, includes singlechip, ultrasonic transmitting circuit and ultrasonic receiving circuit, ultrasonic transmitting circuit includes two way reverse square wave circuit and push-pull inverter circuit, ultrasonic receiving circuit includes leading processing circuit, leading differential amplifier circuit and second order inverting amplifier circuit, the singlechip is connected with two way reverse square wave circuit and push-pull inverter circuit simultaneously, two way reverse square wave circuit are connected with push-pull inverter circuit, leading processing circuit is connected with leading differential amplifier circuit, leading differential amplifier circuit is connected with second order inverting amplifier circuit, second order inverting amplifier circuit is connected with the singlechip.

As the utility model discloses further modified technical scheme, the singlechip adopts chip STM32F103VET 6.

As a further improved technical scheme of the utility model, two way reverse square wave circuit include not gate 74HC04, the PB1 pin NAND gate 74HC04 of singlechip is connected with pin 1, not gate 74HC 04's pin 7 connects the ground wire, and not gate 74HC 04's pin 14 connects the 5V power, not gate 74HC 04's pin 2 is connected with push-pull inverter circuit.

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 an ultrasonic transmitter, the pin 2 of the chip MC34151 is connected to the pin 2 of the nand gate 74HC04, the pin 4 of the chip MC34151 is connected to the pin PB1 of the single chip, the pin 3 of the chip MC34151 is connected to the ground, the pin 6 of the chip MC34151 is connected to the 12V power supply, the pin 7 of the chip MC34151 is connected to the resistor R3, the other end of the resistor R3 is connected to the gate of the MOS transistor Q1, the drain of the MOS transistor Q1 is connected to the capacitor C1 and the resistor R5, the source of the MOS transistor Q1 is grounded, the other end of the resistor R5 is connected to the gate of the transformer, the pin 3415 of the chip MC3415, the other end of the resistor R4 is connected to the gate of the MOS transistor MC 573, the drain electrode of the MOS tube Q2 is simultaneously connected with a capacitor C2 and a resistor R6, the source electrode of the MOS tube Q2 is grounded, the other end of the resistor R6 is connected with the other end of the primary side of the transformer, the center tap end of the transformer is connected with a 12V power supply, and two ends of the secondary side of the transformer are connected with the ultrasonic transmitting device.

As a further improved technical proposal of the utility model, the pre-processing circuit comprises 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, one end of the ultrasonic receiving device is simultaneously connected with one end of a resistor R7 and a capacitor C3, the other end of the ultrasonic receiving device is simultaneously connected with one end of a resistor R7 and a capacitor C4, the other end of the capacitor C3 is simultaneously connected with one end of a resistor R8 and a preposed differential amplifying circuit, the other end of the resistor R8 is connected with the ground wire, the other end of the capacitor C4 is simultaneously connected with one end of the resistor R9 and the preposed differential amplifying circuit, the other end of the resistor R9 is connected with the ground wire, the anode of the diode D1 and the cathode of the diode D2 are both connected with one end of the capacitor C3, the cathode of the diode D1 and the anode of the diode D2 are both connected with one end of the capacitor C4.

As a further improved technical solution of the present invention, the front differential amplifier circuit includes a resistor R10, a resistor R11, a sliding rheostat R12 and an amplifier AD620, one end of the resistor R10 is connected with one end of a capacitor C3, the other end of the resistor R10 is connected with pin 2 of the amplifier AD620, one end of the resistor R11 is connected with one end of the capacitor C4, the other end of the resistor R11 is connected with pin 3 of the amplifier AD620, pin 1 of the amplifier AD620 is connected with pin 8 of the amplifier AD620 through the sliding rheostat R12, pin 5 of the amplifier AD620 is connected with a ground, pin 4 of the amplifier AD620 is connected with a 12V power supply, pin 7 of the amplifier AD620 is connected with a +12V power supply, and pin 6 of the amplifier AD620 is connected with a second-order inverting amplifier circuit.

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 varistor R14, a resistor R15, a resistor R16, a sliding varistor R17, a resistor R18, a first operational amplifier chip OP37 and a second operational amplifier chip OP37, one end of the capacitor C5 is connected to a pin 6 of the amplifier AD620, the other end of the capacitor C5 is connected to one end of the resistor R13, the other end of the resistor R13 is connected to both the sliding varistor R14 and a pin 2 of the first operational amplifier chip OP37, a pin 3 of the first operational amplifier chip OP37 is connected to a ground via a resistor R15, a pin 4 of the first operational amplifier chip OP37 is connected to a 12V power supply, a pin 7 of the first operational amplifier chip OP37 is connected to a +12V power supply, a pin 6 of the first operational amplifier chip OP37 is connected to the other end of the sliding varistor R14 and a pin 6 of the first operational amplifier chip OP37 is connected to a pin 37 via a resistor OP 16, pin 2 of the second operational amplifier chip OP37 is connected with pin 6 of the second operational amplifier chip OP37 through a slide rheostat R17, pin 3 of the second operational amplifier chip OP37 is connected with a ground wire through a resistor R18, pin 4 of the second operational amplifier chip OP37 is connected with a-12V power supply, pin 7 of the second operational amplifier chip OP37 is connected with a +12V power supply, and pin 6 of the second operational amplifier chip OP37 is connected with a pin PA2 of the single chip microcomputer.

The utility model has the advantages that: the utility model relates to an use 51 single chip microcomputer microprocessor as the detection device of control core, the device comprises ultrasonic emission circuit and ultrasonic receiving circuit. The single chip microcomputer triggers the ultrasonic circuit to transmit signals, the signals penetrate between the wood boards to be detected, the ultrasonic receiving circuit receives the returned signals, and the amplitude of the ultrasonic returned signals is detected through a PA2 pin of the single chip microcomputer, so that whether the wood boards to be detected have defects or not is determined, and the detection result is accurate. The whole circuit is simple in design but high in reliability, air is used as a coupling agent, an ultrasonic probe does not need to contact the surface of a workpiece, nondestructive testing of the laminated wood plate is achieved, and some defects of contact type ultrasonic testing are overcome.

Drawings

Fig. 1 is a schematic diagram of a two-way inverse square wave circuit according to the present embodiment.

Fig. 2 is a schematic diagram of a push-pull inverter circuit according to the present embodiment.

FIG. 3 is a schematic diagram of a pre-processing circuit according to the present embodiment.

Fig. 4 is a schematic diagram of the pre-differential amplifier circuit according to the present embodiment.

Fig. 5 is a schematic diagram of a second-order inverting amplifier circuit according to the present embodiment.

Detailed Description

The following further description of embodiments of the present invention is made with reference to fig. 1 to 5:

In the embodiment, the single chip microcomputer adopts a chip STM32F103VET6, is a 32-bit system single chip microcomputer based on ARM Cortex-M3, has the advantages that the main frequency working speed of the chip reaches 72MHz, the speed is high, the efficiency is high, simultaneously onboard resources are rich, and a high-speed memory FLASH and an EEPROM are arranged inside the chip for storing data. The peripheral resources of the chip comprise AD acquisition, USART serial ports, TIMER TIMERs and the like, and further comprise standard communication interfaces: comprising two I²C interface, three SPI, two I²S, one SDIO, five USARTs, one USB, and one CAN. The built-in ARM of STM32F103x is compatible with various development tools, and abundant library functions make the program easier to transplant, simple and convenient, and easy to understand. The internal FLASH can be programmed on line, the processor has low power consumption and high running speed, and is an indispensable part in the embedded field.

In this embodiment, as shown in fig. 1, the two-way inverse square wave circuit includes a not gate 74HC04, a PB1 pin of the single chip microcomputer is connected to a pin 1 of a nand gate 74HC04, a pin 7 of the not gate 74HC04 is connected to a ground, a pin 14 of the not gate 74HC04 is connected to a 5V power supply, and a pin 2 of the not gate 74HC04 is connected to a push-pull inverter circuit.

Because the single chip microcomputer can only generate one path of pulse square wave, one path of signal is connected with the NOT gate 74HC04 to generate an inverse square wave signal. The 74HC04 is a high-speed inverter with 6 sets of NOT gates, and the present embodiment uses one set of inverter to input signal from pin 1 and output signal from pin 2, and the chip has pin 7 connected to ground and pin 14 connected to + 5V power supply. This produces two inverted square wave signals (i.e., two paths A1 and A2).

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, a transformer T1, and an ultrasonic transmitter, where pin 2 of the chip MC34151 is connected to pin 2 of the nand gate 74HC04, pin 4 of the chip MC34151 is connected to a PB1 pin of the single chip, pin 3 of the chip MC34151 is connected to a ground, pin 6 of the chip MC 51 is connected to a +12V power supply, pin 3417 of the chip MC 51 is connected to a resistor R3, the other end of the resistor R3 is connected to a gate of the MOS transistor Q1, a drain of the MOS transistor Q1 is connected to both the capacitor C1 and the resistor R5, a source of the MOS transistor Q1 is grounded, the other end of the resistor R5 is connected to a primary side of the transformer MC34151, a pin 3415 of the chip is connected to a pin 3415, and a pin 58r 4 of the resistor Q57324, the drain electrode of the MOS tube Q2 is simultaneously connected with a capacitor C2 and a resistor R6, the source electrode of the MOS tube Q2 is grounded, the other end of the resistor R6 is connected with the other end of the primary side of the transformer, the center tap end of the transformer is connected with a +12V power supply, and the two ends of the secondary side of the transformer are connected with an ultrasonic wave transmitting device (namely an ultrasonic wave transmitting probe).

Because the ultrasonic probe needs the excitation of a high-frequency high-voltage pulse signal with certain power, a high-frequency small signal generated by the singlechip must be subjected to voltage boosting and power amplification through a high-frequency pulse transformer. Depending on the circuit topology, inverters made of MOSFETs mainly include three types: half bridge, full bridge and push-pull. In the push-pull circuit, the source electrode of the MOS tube is grounded, so that the two groups of circuits do not need to be insulated, and the circuit structure is simple. The excitation voltage of the ultrasonic probe needs to be between 400 and 600V, so a suitable push-pull inverter circuit is designed for the present embodiment.

The two MOS tubes Q1 and Q2 make the primary center end of the transformer alternately conducted with the ground under the action of two square waves. When the MOS tube is conducted, the resistance between the drain and the source is very small, which is equivalent to a short circuit, and the source is grounded, so that the voltage of the drain is pulled down to be low level. When the MOS tube is cut off, the resistance between the drain and the source is very large, which is equivalent to an open circuit, so that the voltage of the drain is equal to the voltage of the center tap end of the transformer, and is high level. Therefore, in the push-pull mode, the two MOS tubes are alternately conducted, and square wave voltage with alternating polarity is formed at the primary side of the transformer.

In this embodiment, the N-channel IRF840 manufactured by IR corporation is selected for the two MOS transistors Q1 and Q2, the maximum operating voltage of the MOS transistor can reach 500V, the on-time is short, and the MOS transistor belongs to a voltage-type driving device and has the advantages of high input impedance, high speed, simple driving circuit and the like.

A driving chip of the MOS tube selects a double-reverse high-voltage high-speed power driver MC34151, the device adopts a highly integrated level conversion technology, and the logic input can accept 3.3V and 5V levels, so that the control of a logic circuit on the power device is simpler, the structure of the driving circuit is simplified, and the reliability is improved. 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, the cost is reduced, and the chip is used as a driving chip of the MOS tube.

Pins

2 and 4 of the MC34151 are connected with input signals,

pins

7 and 5 correspond to output signals of the MC34151, pins 6 are connected with a +12V power supply, and pin 3 is grounded.

The ultrasonic probe selected in the embodiment needs high-frequency high-voltage pulse excitation of 40kHz, and in order to improve the performance of the transformer and reduce the loss of the transformer during working, the magnetic core of the transformer T1 should be made of a material with high saturation magnetic induction intensity, high magnetic permeability, low residual magnetic induction, low loss and good temperature stability, namely a manganese-zinc ferrite magnetic core is selected, and the structure of the magnetic core is EE type.

In this embodiment, as shown in fig. 3, the pre-processing circuit includes an ultrasonic receiving device (i.e. 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, one end of the ultrasonic receiving device is simultaneously connected with one end of a resistor R7 and a capacitor C3, the other end of the ultrasonic receiving device is simultaneously connected with one end of a resistor R7 and a capacitor C4, the other end of the capacitor C3 is simultaneously connected with one end of a resistor R8 and a preposed differential amplifying circuit, the other end of the resistor R8 is connected with the ground wire, the other end of the capacitor C4 is simultaneously connected with one end of the resistor R9 and the preposed differential amplifying circuit, the other end of the resistor R9 is connected with the ground wire, the anode of the diode D1 and the cathode of the diode D2 are both connected with one end of the capacitor C3, the cathode of the diode D1 and the anode of the diode D2 are both connected with one end of the capacitor C4.

The circuit is a pre-processing signal of an ultrasonic receiving circuit, and the main purpose of the circuit is to eliminate direct current offset and amplitude limitation. After the ultrasonic signals are subjected to 'air-wood-air' medium conversion twice, the transmission signals of the ultrasonic signals usually have small direct current signals, and in order to avoid the influence of the signals on an ultrasonic subsequent amplifying circuit, two direct current filtering capacitors C3 and C4 are added into a pre-processing circuit. The amplitude limiting circuit is formed by connecting two backward diodes D1 and D2 in parallel and grounding, and because the ultrasonic transmission signal is weak and cannot enable the diodes to be conducted in a millivolt level, the ultrasonic transmission signal can directly flow into a subsequent amplifying circuit.

In this embodiment, as shown in fig. 4, the pre-differential amplifier circuit includes a resistor R10, a resistor R11, a sliding resistor R12, and an amplifier AD620, one end of the resistor R10 is connected to one end of a capacitor C3, the other end of the resistor R10 is connected to pin 2 of the amplifier AD620, one end of the resistor R11 is connected to one end of the capacitor C4, the other end of the resistor R11 is connected to pin 3 of the amplifier AD620, pin 1 of the amplifier AD620 is connected to pin 8 of the amplifier AD620 through a sliding resistor R12, pin 5 of the amplifier AD620 is connected to a ground, pin 4 of the amplifier AD620 is connected to a-12V power supply, pin 7 of the amplifier AD620 is connected to a +12V power supply, and pin 6 of the amplifier AD620 is connected to a second-order inverting amplifier circuit.

After the ultrasonic waves reach the ultrasonic receiving probe through two medium conversions, the amplitude of a transmission signal is very weak, generally only a dozen millivolts or even a few millivolts, so that the signal must be amplified through a preamplifier. Since the output resistance of the ultrasonic receiving probe is very large, the first-stage amplification circuit must have a sufficiently large input impedance. In the embodiment, the instrumentation amplifier AD620 with high precision, high input impedance, high common mode rejection ratio and low noise is selected as the preamplifier.

In the practical application process of the air coupling type ultrasonic nondestructive testing, the thickness and the material of the tested material are different, so that the size of the ultrasonic transmission signal is greatly different. When the acoustic impedance of the material is not matched with that of air, the excitation voltage is small, and the thickness of the material is large, the amplitude of the received transmission signal is smaller. On the contrary, when the material has high matching degree of acoustic impedance with air, the excitation voltage is large, and the thickness of the material is small, the amplitude of the received transmission signal is larger. Therefore, in order to improve the detection range of the detection device and the adaptability of the device, a controllable gain amplification circuit needs to be designed, which not only meets the requirement of the amplification factor of the ultrasonic air coupling detection, but also does not saturate due to overlarge signals.

The proportional amplifying circuit is divided into two types, one is an in-phase proportional amplifying circuit with high input resistance, and can be regarded as infinite under an ideal state. The other is an inverting proportional amplifying circuit with a small input resistance. After the first stage AD620 differential amplification, the impedance of the ultrasonic transmission signal is already small, so the present embodiment uses the inverse proportion amplification circuit, and the specific structure is shown in fig. 5.

In this embodiment, as shown in fig. 5, the second-order inverting amplifier circuit includes a capacitor C5, a resistor R13, a sliding varistor R14, a resistor R15, a resistor R16, a sliding varistor R17, a resistor R18, a first OP amp chip OP37 and a second OP amp chip OP37, one end of the capacitor C5 is connected to the pin 6 of the amplifier AD620, the other end of the capacitor C5 is connected to one end of the resistor R13, the other end of the resistor R13 is connected to both the sliding varistor R14 and the pin 2 of the first OP amp chip OP37, the pin 3 of the first OP amp chip OP37 is connected to the ground through the resistor R24, the pin 4 of the first OP amp chip OP37 is connected to the-12V power supply, the pin 7 of the first OP amp chip OP37 is connected to the +12V power supply, the pin 6 of the first OP amp chip OP37 is connected to the other end of the sliding varistor R59r 2 and the pin 6 of the first OP amp chip OP37 is connected to the pin 862 through the resistor R84, pin 2 of the second operational amplifier chip OP37 is connected with pin 6 of the second operational amplifier chip OP37 through a slide rheostat R17, pin 3 of the second operational amplifier chip OP37 is connected with a ground wire through a resistor R18, pin 4 of the second operational amplifier chip OP37 is connected with a-12V power supply, pin 7 of the second operational amplifier chip OP37 is connected with a +12V power supply, and pin 6 of the second operational amplifier chip OP37 is connected with a pin PA2 of the single chip microcomputer.

In this embodiment, a detection system using a 51-chip microprocessor as a control core is composed of an ultrasonic transmitting circuit and an ultrasonic receiving circuit. The single chip microcomputer triggers the ultrasonic circuit to transmit signals, the signals penetrate between the wood boards to be detected, the ultrasonic receiving circuit receives the returned signals, and the amplitude of the ultrasonic returned signals is detected through a PA2 pin of the single chip microcomputer, so that whether the wood boards to be detected have defects or not is determined.

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 can be easily conceived by those skilled in the art made by the present technology all fall into the protection scope of the present invention.

Claims

1. The utility model provides an air coupling ultrasonic wave lamination wood board quality detection device which characterized in that: the ultrasonic receiving circuit comprises a preprocessing circuit, a preposed differential amplifying circuit and a second-order inverting amplifying circuit, the singlechip is simultaneously connected with the two reverse square wave circuits and the push-pull inverting circuit, the two reverse square wave circuits are connected with the push-pull inverting circuit, the preprocessing circuit is connected with the preposed differential amplifying circuit, the preposed differential amplifying circuit is connected with the second-order inverting amplifying circuit, and the second-order inverting amplifying circuit is connected with the singlechip.

2. The quality detection device of the air-coupled ultrasonic laminated building board as claimed in claim 1, wherein: the single chip microcomputer adopts a chip STM32F103VET 6.

3. The quality detection device of the air-coupled ultrasonic laminated building board as claimed in claim 2, wherein: the two-way reverse square wave circuit comprises a NOT gate 74HC04, a PB1 pin of the single chip microcomputer is connected with a pin 1 of a NAND gate 74HC04, a pin 7 of the NOT gate 74HC04 is connected with a ground wire, a pin 14 of the NOT gate 74HC04 is connected with a 5V power supply, and a pin 2 of the NOT gate 74HC04 is connected with a push-pull inverter circuit.

4. The quality detection device of the air-coupled ultrasonic laminated building board as claimed in claim 3, wherein: the push-pull inverter circuit comprises a chip MC34151, a resistor R3, a resistor R4, a resistor R5, a resistor R6, a MOS tube Q1, a MOS tube Q2, a capacitor C1, a capacitor C2, a transformer T1 and an ultrasonic transmitting device, wherein a pin 2 of a pin 2 NAND gate 74HC04 of the chip MC34151 is connected with a pin 2, a pin 4 of the chip MC34151 is connected with a pin PB1 of a single chip microcomputer, a pin 3 of the chip MC34151 is connected with a ground wire, a pin 6 of the chip MC34151 is connected with a 12V power supply, a pin 7 of the chip MC34151 is connected with a resistor R3, the other end of the resistor R3 is connected with a gate of a MOS tube Q1, a drain of the MOS tube Q1 is simultaneously connected with a capacitor C1 and a resistor R5, a source of the MOS tube Q3412 is grounded, the other end of the resistor R5 is connected with one end of a primary side of the transformer MC34151, the pin 5 of the chip 341 4 is connected with a resistor R4, the drain of the MOS tube Q2 and the MOS tube Q8672 and the drain, the source electrode of the MOS tube Q2 is grounded, the other end of the resistor R6 is connected with the other end of the primary side of the transformer, the center tap end of the transformer is connected with a 12V power supply, and the two ends of the secondary side of the transformer are connected with the ultrasonic transmitting device.

5. The quality detection device of the air-coupled ultrasonic laminated building board as claimed in claim 4, wherein: the pre-processing circuit comprises 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, wherein one end of the ultrasonic receiving device is simultaneously connected with one ends of a resistor R7 and a capacitor C3, the other end of the ultrasonic receiving device is simultaneously connected with one ends of a resistor R7 and a capacitor C4, the other end of the capacitor C3 is simultaneously connected with one end of a resistor R8 and a pre-differential amplifying circuit, the other end of the resistor R8 is connected with a ground wire, the other end of the capacitor C4 is simultaneously connected with one end of a resistor R9 and the pre-differential amplifying circuit, the other end of the resistor R9 is connected with the ground wire, the anode of the diode D1 and the cathode of the diode D2 are both connected with one end of a capacitor C3, and the cathode of the diode D1 and the anode of the diode D2 are both connected with one end of a capacitor.

6. The quality detection device of the air-coupled ultrasonic laminated building board as claimed in claim 5, wherein: the pre-differential amplifying circuit comprises a resistor R10, a resistor R11, a sliding rheostat R12 and an amplifier AD620, wherein one end of the resistor R10 is connected with one end of a capacitor C3, the other end of the resistor R10 is connected with a pin 2 of the amplifier AD620, one end of the resistor R11 is connected with one end of the capacitor C4, the other end of the resistor R11 is connected with a pin 3 of the amplifier AD620, a pin 1 of the amplifier AD620 is connected with a pin 8 of the amplifier AD620 through a sliding rheostat R12, a pin 5 of the amplifier AD620 is connected with the ground, a pin 4 of the amplifier AD620 is connected with a-12V power supply, a pin 7 of the amplifier AD620 is connected with a +12V power supply, and a pin 6 of the amplifier AD620 is connected with a second-order inverting amplifying circuit.

7. The quality detection device of the air-coupled ultrasonic laminated building board as claimed in claim 6, wherein: the second-order inverting amplifying circuit comprises 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 OP-amp chip OP37 and a second OP-amp chip OP37, wherein one end of the capacitor C5 is connected with a pin 6 of the amplifier AD620, the other end of the capacitor C5 is connected with one end of the resistor R13, the other end of the resistor R13 is simultaneously connected with the sliding rheostat R14 and a pin 2 of the first OP-amp chip OP37, a pin 3 of the first OP-amp chip OP37 is connected with the ground through a resistor R15, a pin 4 of the first OP-amp chip OP37 is connected with a 12V power supply, a pin 7 of the first OP-amp chip OP37 is connected with a +12V power supply, a pin 6 of the first OP-amp chip 37 is connected with the other end of the sliding rheostat R37, a pin 6 of the first OP-amp chip OP 72 is connected with a pin of the second OP-amp chip OP 2 through a resistor R37, and a pin of the second OP-amp chip OP-amp chip 37 is connected with a pin of the second, the pin 3 of the second operational amplifier chip OP37 is connected with the ground wire through a resistor R18, the pin 4 of the second operational amplifier chip OP37 is connected with a 12V power supply, the pin 7 of the second operational amplifier chip OP37 is connected with a 12V power supply, and the pin 6 of the second operational amplifier chip OP37 is connected with a PA2 pin of the single chip microcomputer.