Ultrasonic detection device capable of controlling coupling strength and method thereof

Abstract

The invention provides an ultrasonic detection device capable of controlling coupling strength and a method thereof, and belongs to the technical field of nondestructive testing, and the method comprises the following steps: device state and adjustment, ultrasonic sensor installation and position setting, a motor driving a screw rod to stretch out, pressure closed-loop control starting, and motor rotation control through a PID algorithm. And performing signal acquisition operation and device resetting. In the aspect of precision, the force can be accurately controlled in a specific range, the coupling strength is flexibly adjusted according to material characteristics, good acoustic coupling is formed, coupling layer interference is avoided, and the detection precision and the signal quality are greatly improved. The cost advantage is prominent, the hardware cost is greatly reduced, force is accurately controlled, probe abrasion is reduced, and the maintenance and replacement cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of nondestructive testing, and particularly to an ultrasonic testing device with controllable coupling force and a method thereof. Background Art

[0002] As one of the core technologies in the field of nondestructive testing, ultrasonic testing is widely used in fields such as aerospace, energy pipelines, rail transit, and structural health monitoring of buildings. Its non-invasive and highly sensitive characteristics make it the preferred solution for detecting internal defects such as cracks and cavities in structures. However, the signal quality of ultrasonic testing is closely related to the stability of the coupling interface pressure. When the coupling pressure between the probe and the object to be measured fluctuates too much, it will significantly affect the acoustic wave transmittance and lead to a decrease in the defect detection rate.

[0003] In the prior art, the method of manual coupling relying on the operator's experience to apply pressure has systematic defects: the coupling pressure applied by the operator has a large discreteness, resulting in a low qualified rate for single detection. Usually, it is necessary to repeat the coupling 3 - 5 times to meet the detection requirements, which seriously restricts the detection efficiency. In addition, the current high-precision pressure control equipment is costly and difficult to meet the needs of large-scale promotion. Summary of the Invention

[0004] The purpose of the present invention is to provide an ultrasonic testing device with controllable coupling force and a method thereof, so as to solve the technical problem that the coupling pressure applied by the existing manual coupling has a large discreteness, resulting in a low qualified rate for single detection. Usually, it is necessary to repeat the coupling 3 - 5 times to meet the detection requirements, which seriously restricts the detection efficiency.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A method for an ultrasonic testing device with controllable coupling force, the ultrasonic testing device includes a motor, an upper slide plate, a compression force detection mechanism, an ultrasonic sensor, a lead screw, and a controller. The output end of the motor is connected to one end of the lead screw. The sliding sleeve on the lead screw is connected to the upper slide plate and drives the upper slide plate to move back and forth. The compression force detection mechanism is arranged at the front end of the upper slide plate and moves back and forth with the upper slide plate. The ultrasonic sensor is arranged at the front end of the compression force detection mechanism. The controller is respectively connected to the compression force detection mechanism, the ultrasonic sensor, and the motor;

[0007] The method includes the following: device status and adjustment, installation and position setting of the ultrasonic sensor, the motor drives the lead screw to extend, the pressure closed-loop control is started, the motor rotation is controlled by the PID algorithm, signal acquisition operation, and device reset.

[0008] Furthermore, the ultrasonic detection device further includes a fixing plate. The motor is fixedly arranged at one end of the fixing plate. The lead screw passes through the fixing plate. The compression force detection mechanism includes a spring column and a three-jaw chuck. The three-jaw chuck is arranged at the front end of the spring column. The rear end of the spring column is fixedly connected to the upper slide plate.

[0009] Furthermore, the spring column includes a housing, a pressure sensor and a spring. The pressure sensor is arranged inside the housing. One end of the spring is arranged on the pressure sensor, and the other end of the spring is connected to the chuck base of the three-jaw chuck. The chuck base is clamped inside the housing, and the three-jaw chuck is arranged to move with the telescopic movement of the spring.

[0010] Furthermore, the ultrasonic detection device further includes a sliding support. The sliding support is slidably arranged at the bottom end of the fixing plate. The sliding support is arranged in an L-shaped structure. A round hole is arranged at the front end of the L-shaped structure. The ultrasonic sensor is arranged opposite to the round hole, and the ultrasonic sensor can pass through the round hole.

[0011] Furthermore, the specific process of the device state and adjustment is as follows:

[0012] In the non-working state, the whole device is in a folded state to save space and facilitate storage. When coupling operation is required, first pull out the sliding support from the folded state to the workable position. The bottom of the sliding support is equipped with a magnetic adsorption module and a vacuum adsorption module interface, and the appropriate fixing method can be selected according to the material and surface characteristics of the object to be measured. If the object to be measured is a magnetic material, install the magnetic adsorption module. If it is a non-magnetic and relatively flat and smooth object, then select the vacuum adsorption module.

[0013] Furthermore, the specific process of the installation and position setting of the ultrasonic sensor is as follows:

[0014] After the sliding support is ready, install the ultrasonic probe on the self-tightening three-jaw chuck fixture at the head of the spring column. The fixture is designed to be self-tightening to ensure that the probe is firmly and stably installed. At this time, the spring column is in a natural elongation state. Through precise mechanical design and installation debugging, the probe is kept at an initial distance of 30 mm from the measured surface. The initial distance provides a starting position for the subsequent coupling operation, which can not only avoid the collision and damage between the ultrasonic sensor and the object to be measured, but also ensure that the coupling action starts within a reasonable distance range.

[0015] Furthermore, the specific process of the motor driving the lead screw to extend is as follows:

[0016] After the coupling preparation is completed, the system starts the coupling process. The motor operates to drive the lead screw to rotate and starts to extend at a constant speed of 2 mm / s. The motor cooperates with the lead screw to achieve precise linear displacement output. Since the step angle of the motor is 1.8°, through the precise control of the motor driver board for the motor, each step pulse corresponds to a set displacement of the lead screw. The operation of the motor is stable and precise, ensuring that the lead screw approaches the object to be measured at a stable speed.

[0017] Further, the specific process of starting the pressure closed-loop control is as follows:

[0018] As the lead screw extends, the ultrasonic sensor gradually approaches the surface to be measured. When the probe of the ultrasonic sensor touches the surface to be measured, the spring column starts to be compressed. At this time, the pressure sensor starts to work and continuously collects the coupling pressure signal generated by the compression of the spring column. The change in pressure will cause the resistance value of the spring column to change, and then generate a corresponding change in the electrical signal. After the amplified signal is subjected to analog-to-digital conversion by the HX711 module, it is connected to the GPIO pins of the STM32 controller through the DATA pin and the SCK pin, and the digital signal is transmitted to the controller by using the serial communication method.

[0019] Further, the specific process of controlling the rotation of the motor by the PID algorithm is as follows:

[0020] After receiving the amplified pressure data, the controller immediately processes the data using the PID algorithm. The PID algorithm compares the currently collected pressure value with the pre-set pressure value, calculates the deviation between the two. If the current pressure value is lower than the preset value, the PID algorithm calculates a positive value according to the calculation rule. The positive value represents that the elongation of the lead screw needs to be increased to increase the coupling pressure. Then, the controller converts the calculation result into a corresponding pulse signal and outputs it to the motor driver board. The motor driver board controls the operation of the motor according to the received pulse signal, making the lead screw extend further, thereby adjusting the coupling pressure. On the contrary, if the current pressure value is higher than the preset value, the PID algorithm calculates a negative value, and the controller outputs a corresponding pulse signal to make the motor reverse and the lead screw contract to reduce the coupling pressure. During the whole process, the pressure sensor continuously and real-time collects the pressure signal, and the controller continuously performs PID operations and pulse signal outputs according to the newly collected data, so as to achieve precise control of the dynamic adjustment of the lead screw displacement by the motor until the coupling pressure is stabilized within the range of ±5% of the set value.

[0021] Due to the adoption of the above technical solutions, the present invention has the following beneficial effects:

[0022] In terms of the precision of the present invention, it can accurately control the force within a specific range, flexibly adjust the coupling force according to the material characteristics, form good acoustic coupling, avoid the interference of the coupling layer, and greatly improve the detection precision and signal quality. It has prominent cost advantages, significantly reducing the hardware cost. The precise force control reduces the probe wear and lowers the maintenance and replacement costs. It has strong adaptability. The modular design is compatible with mainstream probes. The dual adsorption mode adapts to complex working conditions. The adjustable coupling force can be adapted to different materials and complex environments, broadening the detection range. In terms of high efficiency and stability, the closed-loop control eliminates the artificial discreteness, greatly improving the detection efficiency. It can quickly reach the optimal state, reduce the detection preparation work, and is convenient to be integrated into the automated detection process, improving the detection efficiency and quality of the production line. In terms of operation convenience, the folding design of the sliding support and the flexible fixing methods of magnetic attraction and vacuum adsorption are more convenient for installation and storage compared with the traditional fixing mode. In terms of system stability, the built-in spiral spring in the spring column increases flexibility, avoids the damage risk caused by rigid contact, and improves the overall stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is a schematic structural diagram of the ultrasonic detection device of the present invention;

[0024] Figure 2 is a schematic structural diagram of the lead screw of the present invention;

[0025] Figure 3 is a structural diagram of the three-jaw chuck and the spring column of the present invention;

[0026] Figure 4 is a schematic internal structure diagram of the spring column of the present invention;

[0027] Figure 5 is a schematic structural diagram of the sliding support of the present invention;

[0028] Figure 6 is a working flow diagram of the device of the present invention.

[0029] In the drawings, 1 - motor, 2 - upper slide plate, 3 - spring column, 4 - sliding support, 5 - three-jaw chuck, 6 - ultrasonic sensor, 7 - round hole, 8 - lead screw, 9 - pressure sensor, 10 - spring, 11 - chuck base. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] To make the objectives, technical solutions and advantages of the present invention more clearly understood, the following preferred embodiments are cited with reference to the accompanying drawings for further detailed description of the present invention. However, it should be noted that many details listed in the specification are only for enabling the reader to have a thorough understanding of one or more aspects of the present invention, and these aspects of the present invention can be implemented even without these specific details.

[0031] As Figure 1-6As shown in the figure, a method for an ultrasonic detection device with controllable coupling force. The ultrasonic detection device includes a motor 1, an upper slide plate 2, a compression force detection mechanism, an ultrasonic sensor 6, a lead screw 8, and a controller. The output end of the motor 1 is connected to one end of the lead screw 8. The sliding sleeve on the lead screw 8 is connected to the upper slide plate 2 and drives the upper slide plate 2 to move back and forth. The compression force detection mechanism is arranged at the front end of the upper slide plate 2 and moves back and forth with the upper slide plate 2. The ultrasonic sensor 6 is arranged at the front end of the compression force detection mechanism. The controller is respectively connected to the compression force detection mechanism, the ultrasonic sensor 6, and the motor 1. The motor 1 and the lead screw 8 can be replaced by a cylinder.

[0032] The ultrasonic detection device further includes a fixing plate. The motor 1 is fixedly arranged at one end of the fixing plate. The lead screw 8 passes through the fixing plate. The compression force detection mechanism includes a spring column 3 and a three-jaw chuck 5. The three-jaw chuck 5 is arranged at the front end of the spring column 3. The rear end of the spring column 3 is fixedly connected to the upper slide plate 2.

[0033] The spring column 3 includes a housing, a pressure sensor 9, and a spring 10. The pressure sensor 9 is arranged inside the housing. One end of the spring 10 is arranged on the sensor of the pressure sensor 9. The other end of the spring 10 is connected to the chuck base 11 of the three-jaw chuck 5. The chuck base 11 is clamped inside the housing. The three-jaw chuck 5 moves back and forth with the expansion and contraction of the spring 10.

[0034] The ultrasonic detection device further includes a sliding support 4. The sliding support 4 is slidably arranged at the bottom end of the fixing plate. The sliding support 4 is arranged in an L-shaped structure. A round hole 7 is arranged at the front end of the L-shaped structure. The ultrasonic sensor 6 is arranged opposite to the round hole 7 and the ultrasonic sensor 6 can pass through the round hole 7.

[0035] The method includes the following:

[0036] S1. Device status and adjustment

[0037] In the non-working state, the entire device is in a folded state to save space and facilitate storage. When coupling operation is required, first pull out the sliding support 4 from the folded state to make it in a workable position. The sliding support 4 is made of 6061 aluminum alloy frame, which is strong and light. Its bottom is equipped with a magnetic adsorption module and a vacuum adsorption module interface, and the appropriate fixing method can be selected according to the material and surface characteristics of the object to be measured. If the object to be measured is a magnetic material, the magnetic adsorption module can be installed; if it is a non-magnetic and relatively flat and smooth object, the vacuum adsorption module can be selected.

[0038] S2. Probe installation and position setting

[0039] After the sliding support 4 is ready, install the ultrasonic probe on the self-tightening three-jaw fixture at the head of the spring column 3. This fixture is designed to be self-tightening and can conveniently and quickly clamp various mainstream industrial probes, ensuring that the probe is firmly and stably installed. At this time, the spring column is in a natural elongation state. Through precise mechanical design and installation debugging, the probe is kept at an initial distance of 30 mm from the measured surface. This initial distance provides a suitable starting position for subsequent coupling operations, which can not only avoid the probe from colliding and damaging the measured object but also ensure that the coupling action starts within a reasonable distance range.

[0040] S3. Motor screw rod extends

[0041] After the coupling preparation is completed, the system starts the coupling process. The screw rod 8 starts to extend at a constant speed of 2 mm / s under the control of the controller (STM32 controller). The motor cooperates with the ball screw to achieve precise linear displacement output. Since the step angle of the motor is 1.8°, through the precise control of the motor driver board for the motor, each step pulse corresponds to a certain screw rod displacement. During this process, the motor runs smoothly and precisely, ensuring that the ultrasonic sensor 6 approaches the measured object at a stable speed.

[0042] S4. Pressure closed-loop control starts

[0043] As the screw rod 8 extends, the ultrasonic probe gradually approaches the measured surface. The moment the probe touches the measured surface, the spring column 3 starts to be compressed. At this time, the pressure sensor 9 (full-bridge strain gauge sensor) starts to work, and in real-time collects the coupling pressure signal generated due to the compression of the spring column. The change in pressure will cause the resistance value of the full-bridge strain gauge sensor to change, and then generate a corresponding change in the electrical signal. These weak electrical signals are transmitted to the HX711 module for amplification. After the amplified signal is subjected to analog-to-digital conversion by the HX711 module, it is connected to the GPIO pins of the STM32 controller through the DATA pin and the SCK pin, and the digital signal is transmitted to the controller in a serial communication manner.

[0044] S5. PID algorithm controls the motor

[0045] After the controller receives the amplified pressure data, it immediately processes the data using the PID algorithm. The PID algorithm compares the currently collected pressure value with the pre-set pressure value and calculates the deviation between the two. For example, if the current pressure value is lower than the preset value, the PID algorithm will calculate a positive value according to its calculation rules, and this positive value represents the amount by which the elongation of the lead screw 8 needs to be increased to increase the coupling pressure. Then, the controller converts this calculation result into a corresponding pulse signal and outputs it to the motor driver board. The motor driver board controls the operation of the 42 motor according to the received pulse signal, causing the lead screw 8 to further elongate, thereby adjusting the coupling pressure. Conversely, if the current pressure value is higher than the preset value, the PID algorithm will calculate a negative value, and the controller outputs a corresponding pulse signal to reverse the motor and contract the lead screw 8 to reduce the coupling pressure. During the entire process, the pressure sensor 9 continuously and real-time collects pressure signals, and the controller continuously performs PID operations and pulse signal outputs based on the newly collected data, thereby achieving precise control of the dynamic adjustment of the lead screw displacement by the motor until the coupling pressure is stabilized within ±5% of the set value.

[0046] The controller is based on an STM32 microcontroller (main frequency 168 MHz), with a built-in PID algorithm, and dynamically adjusts the lead screw displacement according to the feedback of the pressure sensor. The control equation is as follows:

[0047]

[0048] e(t) is the error signal, representing the difference between the expected value and the actual value, K p 、K i 、K d are the proportional gain, integral gain, and derivative gain respectively. The PID parameters are tuned by the Ziegler-Nichols method to achieve a control accuracy of ±5%.

[0049] S6. Signal acquisition operation

[0050] When the coupling pressure is stabilized within ±5% of the set value, it means that the coupling process is successfully completed. At this time, the operator starts the signal acquisition step. Under the stable coupling pressure, the ultrasonic probe can effectively emit ultrasonic signals to the object to be measured and receive the reflected signals. These collected signals can be used for subsequent analysis and detection of the internal structure, defects, etc. of the object to be measured.

[0051] S7. Device reset process

[0052] After the operator completes signal acquisition, the system enters the reset process. The controller sends an instruction to make the motor driver board control the 42 motor to reverse, and the lead screw starts to retract. As the lead screw retracts, the pressure on the spring column gradually decreases, and the spring column 3 resumes its extended state, driving the ultrasonic probe away from the object to be measured and finally returning to the initial ready position. At this time, the entire device has completed a complete coupling and signal acquisition operation and is waiting for the next task instruction. During the reset process, if the sliding support 4 is no longer needed, it can be restored to the folded form in the non-working state through the folding operation for easy storage and placement.

[0053] (1) High-precision control: The control accuracy reaches ±5% within the range of 0.5 - 8N, and the single-coupling qualification rate is increased to over 93%; it can adjust the coupling force according to the surface roughness, material and other characteristics of the material to be detected to ensure good acoustic coupling between the probe and the workpiece surface, thereby improving the detection accuracy; accurately controlling the coupling force can avoid the influence of too thick or too thin coupling layer on ultrasonic propagation, reduce signal attenuation and noise interference, and improve the accuracy and reliability of the detection signal.

[0054] (2) Low cost: The hardware cost is reduced by more than 60% compared with the traditional automation solution (controlled within 500 yuan); by accurately controlling the coupling force, excessive friction between the probe and the workpiece surface can be avoided, reducing the wear of the probe and extending its service life; since the loss of components such as the probe is reduced, the maintenance cost and replacement frequency of the equipment are reduced, saving costs for users.

[0055] (3) Strong adaptability: The modular quick-release design is compatible with mainstream probes, and the magnetic adsorption and vacuum adsorption dual modes support complex working conditions installation; the adjustable coupling force enables the device to adapt to the detection needs of different materials. Whether it is metal, plastic or composite material, suitable coupling conditions can be found to expand the detection range; in complex or special detection environments, such as high temperature, high pressure, etc., by adjusting the coupling force, effective coupling between the probe and the workpiece can be ensured to ensure the smooth progress of the detection.

[0056] (4) High efficiency and stability: The closed-loop control eliminates the discreteness of manual operation, and the detection efficiency is increased by more than 50%. Traditional ultrasonic detection may take time to prepare the coupling agent or adjust the probe position, while the device with controllable coupling force can quickly adjust to the best state, reducing the preparation work before detection and improving the detection efficiency; it is easy to combine with the automated detection system. By accurately controlling the coupling force, an automated and highly efficient detection process can be realized, improving the detection efficiency and quality of the production line.

[0057] The spring column is internally provided with a helical spring, and its head is equipped with an existing self-tightening three-jaw clamp or three-jaw chuck, which is compatible with mainstream industrial probes (diameter 10 - 25 mm), and the adjustable range of the clamping force is 5 - 20 N. The sliding support uses a 6061 aluminum alloy frame, supporting dual-mode installation of magnetic adsorption (adsorption force ≥ 30 N) and vacuum adsorption (vacuum degree -80 kPa), and is suitable for rough surfaces (Ra ≤ 6.3 μm). It can be folded in the non-working state and fixed on the surface of the object to be measured by magnetic adsorption or vacuum adsorption in the working state.

[0058] Workflow:

[0059] ① Preparation before coupling

[0060] In the non-working state, the device is in a folded state. Before coupling, the sliding support 4 of the device needs to be pulled out, the probe is connected, the magnetic adsorption module or vacuum adsorption module is installed, and then it is fixed on the surface of the object to be measured. At this time, the spring column 3 is in a natural elongation state, and the probe is 30 mm away from the measured surface.

[0061] ② Start coupling

[0062] The lead screw 8 extends at a speed of 2 mm / s. After the ultrasonic probe contacts the measured surface, the spring column 3 is compressed, triggering pressure closed-loop control: the pressure sensor 9 collects pressure signals in real time → the controller calculates the pressure deviation and outputs a pulse signal → the motor dynamically adjusts the displacement of the lead screw until the pressure is stable within the range of ±5% of the set value.

[0063] ③ Complete coupling

[0064] After the pressure is stable, the operator completes the signal acquisition step. After the acquisition is completed, the lead screw 8 retracts, the probe moves away from the object to be measured, and the spring column 3 returns to the elongation state.

[0065] Matters not covered in this invention are well-known technologies.

[0066] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can still be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A method for an ultrasonic detection device with controllable coupling strength, characterized in that: The ultrasonic detection device includes a motor (1), an upper slide plate (2), a compression force detection mechanism, an ultrasonic sensor (6), a lead screw (8) and a controller. The output end of the motor (1) is connected to one end of the lead screw (8). The sliding sleeve on the lead screw (8) is connected to the upper slide plate (2) and drives the upper slide plate (2) to move back and forth. The compression force detection mechanism is arranged at the front end of the upper slide plate (2) and moves back and forth with the upper slide plate (2). The ultrasonic sensor (6) is arranged at the front end of the compression force detection mechanism. The controller is respectively connected to the compression force detection mechanism, the ultrasonic sensor (6) and the motor (1). The method includes the following: device state and adjustment, installation and position setting of the ultrasonic sensor (6), the motor (1) drives the lead screw (8) to extend, the pressure closed-loop control is started, the motor (1) is controlled to rotate through the PID algorithm, signal acquisition operation and device reset.

2. The method of an ultrasonic detection device with controllable coupling strength according to claim 1, characterized in that: The ultrasonic detection device further includes a fixing plate. The motor (1) is fixedly arranged at one end of the fixing plate. The lead screw (8) passes through the fixing plate. The compression force detection mechanism includes a spring column (3) and a three-jaw chuck (5). The three-jaw chuck (5) is arranged at the front end of the spring column (3). The rear end of the spring column (3) is fixedly connected to the upper slide plate (2).

3. The method of an ultrasonic detection device with controllable coupling strength according to claim 2, characterized in that: The spring column (3) includes a housing, a pressure sensor (9) and a spring (10). The pressure sensor (9) is arranged inside the housing. One end of the spring (10) is arranged on the pressure sensor (9). The other end of the spring (10) is connected to the chuck base (11) of the three-jaw chuck (5). The chuck base (11) is clamped inside the housing. The three-jaw chuck (5) moves back and forth with the telescopic movement of the spring (10).

4. The method of an ultrasonic detection device with controllable coupling strength according to claim 1, characterized in that: The ultrasonic detection device further includes a sliding support (4). The sliding support (4) is slidably arranged at the bottom end of the fixing plate. The sliding support (4) is arranged in an L-shaped structure. A round hole (7) is arranged at the front end of the L-shaped structure. The ultrasonic sensor (6) is arranged opposite to the round hole (7), and the ultrasonic sensor (6) can pass through the round hole (7).

5. The method of an ultrasonic detection device with controllable coupling strength according to claim 1, characterized in that: The specific process of device state and adjustment is as follows: In the non-working state, the whole device is in a folded state to save space and facilitate storage. When coupling operation is required, first pull out the sliding support (4) from the folded state to the workable position. The bottom of the sliding support (4) is equipped with a magnetic adsorption module and a vacuum adsorption module interface. The appropriate fixing method can be selected according to the material and surface characteristics of the object to be measured. If the object to be measured is a magnetic material, install the magnetic adsorption module. If it is a non-magnetic and relatively flat and smooth object, select the vacuum adsorption module.

6. The method of an ultrasonic detection device with controllable coupling strength according to claim 1, characterized in that: The specific process of installation and position setting of the ultrasonic sensor (6) is as follows: After the sliding support (4) is ready, install the ultrasonic probe on the self-tightening three-jaw chuck (5) fixture at the head of the spring column (3). The fixture is designed to be self-tightening to ensure that the probe is firmly and stably installed. At this time, the spring column (3) is in a natural elongation state. Through precise mechanical design and installation debugging, the probe is kept at an initial distance of 30 mm from the measured surface. This initial distance provides a starting position for subsequent coupling operations, which can not only prevent the ultrasonic sensor (6) from colliding and damaging with the measured object but also ensure that the coupling action starts within a reasonable distance range.

7. The method of an ultrasonic detection device with controllable coupling strength according to claim 1, characterized in that: The specific process of the motor (1) driving the lead screw (8) to extend is as follows: After the coupling preparation work is completed, the system starts the coupling process. The motor operates to drive the lead screw (8) to rotate and starts to extend at a constant speed of 2 mm / s. The motor cooperates with the lead screw to achieve precise linear displacement output. Since the stepping angle of the motor is 1.8°, through the precise control of the motor by the motor driver board, each stepping pulse corresponds to a set displacement of the lead screw. The motor runs smoothly and precisely, ensuring that the lead screw (8) approaches the measured object at a stable speed.

8. The method of an ultrasonic detection device with controllable coupling strength according to claim 1, characterized in that: The specific process of starting the pressure closed-loop control is as follows: As the lead screw (8) extends, the ultrasonic sensor (6) gradually approaches the measured surface. When the probe of the ultrasonic sensor (6) touches the measured surface instantaneously, the spring column (3) starts to be compressed. At this time, the pressure sensor (9) starts to work and continuously collects the coupling pressure signal generated by the compression of the spring column (3). The change in pressure will cause the resistance value of the spring column (3) to change, and then generate a corresponding change in the electrical signal. The electrical signal is amplified and processed, and the amplified signal is connected to the GPIO pin of the STM32 controller through the pin and transmitted to the controller.

9. The method of an ultrasonic detection device with controllable coupling strength according to claim 1, characterized in that: The specific process of controlling the rotation of the motor (1) through the PID algorithm is as follows: After receiving the amplified pressure data, the controller immediately processes the data using the PID algorithm. The PID algorithm compares the currently collected pressure value with the pre-set pressure value and calculates the deviation between the two. If the current pressure value is lower than the preset value, the PID algorithm calculates a positive value according to the calculation rule. The positive value represents that the elongation of the lead screw (8) needs to be increased to increase the coupling pressure. Then, the controller converts the calculation result into a corresponding pulse signal and outputs it to the motor driver board. The motor driver board controls the operation of the motor according to the received pulse signal, making the lead screw (8) further extend, thereby adjusting the coupling pressure. On the contrary, if the current pressure value is higher than the preset value, the PID algorithm calculates a negative value, and the controller outputs a corresponding pulse signal to make the motor reverse and the lead screw (8) contract to reduce the coupling pressure. Throughout the process, the pressure sensor (9) continuously and real-time collects the pressure signal, and the controller continuously performs PID operations and pulse signal outputs according to the newly collected data, so as to achieve precise control of the dynamic adjustment of the lead screw displacement by the motor until the coupling pressure is stabilized within ±5% of the set value.

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