Ultrasonic Flaw Detector is a portable industrial non-destructive testing instrument that can detect, locate, evaluate and diagnose various defects (cracks, looseness, pores, inclusions, etc.) inside the workpiece quickly, easily, without damage and accurately. It can be used in both laboratories and engineering sites.
Shanghai Bashu is an ultrasonic flaw detector
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Today, Bayu will introduce you to the working principle of the ultrasonic flaw detector.
Ultrasonic flaw detector
working principle
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When the ultrasonic wave propagates in the material to be tested, the acoustic properties of the material and the change of the internal structure have a certain influence on the propagation of the ultrasonic wave. The technique of understanding the material properties and structural changes by detecting the degree and condition of the ultrasonic wave is called ultrasonic testing. Ultrasonic testing methods generally include a penetrating method, a pulse reflecting method, a tandem method, and the like.
Digital ultrasonic flaw detectors usually send ultrasound to the object to be measured (such as industrial materials, human body), and then use its reflection, Doppler effect, transmission, etc. to obtain information inside the object under test and process it to form an image.
Doppler effect method
Is to use the Doppler shift effect that occurs when the ultrasonic encounters a moving object to derive the characteristics of the moving direction and speed of the object;
Transmission method
The internal characteristics of the object are obtained by analyzing the changes after the ultrasonic wave penetrates the object to be measured, and its application is still in the development stage;
Reflection method
The ultrasonic flaw detector here mainly introduces the most widely used method for obtaining the internal characteristic information of the object by the reflection method.
The reflection method is based on the principle that ultrasonic waves will have strong reflections when organizing interfaces through different acoustic impedances. As we know, sound waves are transmitted from one medium to another at the interface between the two. Reflection will occur, and the greater the difference between the media, the larger the reflection will be, so we can emit an ultrasonic wave that is strong and capable of linear propagation to an object. The ultrasonic flaw detector then receives the reflected ultrasonic wave and according to The order and amplitude of the reflected ultrasonic waves can determine the size and distribution of the various media contained in the tissue and the degree of contrast between the various media (the ultrasonic waves reflected back can reflect The distance from the reflection surface to the detection surface, the amplitude can reflect the characteristics of the size of the medium, the degree of contrast difference, etc., and the ultrasonic flaw detector determines whether the object to be measured is abnormal. In this process, there are many aspects involved, including the generation, reception, signal conversion and processing of ultrasonic waves.
The method for generating ultrasonic waves is to generate an excitation electric signal through a circuit to transmit a crystal having a piezoelectric effect (such as quartz, lithium sulfate, etc.) to vibrate to generate ultrasonic waves; and when receiving the reflected ultrasonic waves, the piezoelectric crystal is again The electric signal is generated by the pressure of the reflected sound wave and transmitted to the signal processing circuit for a series of processing, and the ultrasonic flaw detector finally forms an image for observation and judgment.
Here, the type of the image processing method (that is, the image into which the obtained signal is converted) can be further classified into an A-type display, an M-type display, a B-type display, a C-type display, an F-type display, and the like.
The A-type display processes the received ultrasonic signal into a waveform image. According to the shape of the waveform, it can be seen whether there are abnormalities and defects in the measured object, and how large, etc., the ultrasonic flaw detector is mainly used for industrial detection;
The M-type display is a chronological expansion of a luminance-processed detection information to form a one-dimensional "space multi-point motion timing diagram" suitable for observing internal moving objects, ultrasonic flaw detectors such as moving organs and arteries. Blood vessels, etc.
The B-type display is a two-dimensional "anatomical image" that combines a plurality of brightness-processed detection information side by side to reflect the internal tomographic section of the measured object (the B-mode used in hospitals is made by this principle). ), the ultrasonic flaw detector is suitable for observing objects that are static inside;
The C-type display is also an image display. The abscissa and ordinate of the flaw detector screen are mechanically scanned to represent the position of the probe on the surface of the workpiece. The amplitude of the received signal of the probe is expressed by the brightness of the spot. Therefore, when the probe moves on the surface of the workpiece, the flat image of the internal defect of the workpiece is displayed on the screen, but the depth of the defect cannot be displayed.
The C-type display and the F-type display are now used less.
Ultrasonic flaw detector detection can not only be very accurate, but also more convenient and faster than other detection methods, and it will not cause harm to the detection object and the operator. Therefore, it is more and more popular and popular. Development prospects.
Shanghai Bayu (
In 2007, Industrial Co., Ltd. set up an offline supply system for laboratory instruments, MRO industrial products, etc. In 2009, it officially launched an online procurement operation platform. As the earliest enterprise engaged in MRO industrial products and laboratory instruments and meters in Shanghai, Shanghai Bayu Industrial Co., Ltd. has strong strength, scientific management, quality assurance, complete after-sales and reputation first. 
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Semiconductor Moly
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