Classification Of Flaw Detection Display Methods Of Ultrasonic Flaw Detector

Ultrasonic flaw detector is the most commonly used method in the field of flaw detection. It has many advantages such as easy to carry, easy to operate, and accurate measurement.
Ultrasonic flaw detector mainly introduces the method of obtaining internal characteristic information of objects through the reflection method which is widely used at present. The reflection method is based on the principle that ultrasound will be strongly reflected when it passes through the tissue interface with different acoustic impedances. Reflection will occur, and the greater the difference between the media, the greater the reflection, so we can emit ultrasonic waves that have strong penetrating power and can propagate in a straight line to an object. The ultrasonic flaw detector then receives the reflected ultrasonic waves and uses them according to The sequence and amplitude of these reflected ultrasonic waves can determine the size and distribution of various media contained in the tissue, as well as the degree of contrast between various media and other information (the sequence of reflected ultrasonic waves can reflect The distance between the reflection interface and the detection surface, and the amplitude can reflect the size of the medium, the degree of contrast difference and other characteristics), and the ultrasonic flaw detector can judge whether the object under test is abnormal. In this process, many aspects are involved, including ultrasonic generation, reception, signal conversion and processing, etc. The method of generating ultrasonic waves is to generate an excitation signal through a circuit and transmit it to a crystal with piezoelectric effect (such as quartz, lithium sulfate, etc.), so that it vibrates to generate ultrasonic waves; when receiving the reflected ultrasonic waves, the piezoelectric crystal It will be subjected to the pressure of the reflected sound wave to generate an electrical signal and send it to the signal processing circuit for a series of processing, and then form an image for people to observe and judge.
Ultrasonic flaw detectors can be divided into A-type display, M-type display, B-type display, C-type display, F-type display, etc. according to the type of image processing method (that is, what form of image the obtained signal is converted into). Among them, the A-type display is to process the received ultrasonic signal into a waveform image. According to the shape of the waveform, it can be seen whether there is any abnormality in the object under test, where the defect is, and how big it is. Ultrasonic flaw detectors are mainly used for industrial testing; M-type The display is to expand a piece of detection information processed by brightness in time order to form a one-dimensional "spatial multi-point motion timing diagram", which is suitable for observing internal moving objects, such as moving organs, arteries, etc. The B-type display is a two-dimensional "anatomical image" that combines many pieces of detection information that have been processed in parallel and reflects the internal section of the measured object (the B-type ultrasound used in the hospital is based on this principle) ), the ultrasonic flaw detector is suitable for observing objects that are static inside; while the C-type display and F-type display are less used now. Ultrasonic flaw detector detection can not only be very accurate, but also more convenient and faster than other detection methods, and will not cause harm to the detection object and the operator, so it is more and more popular among people and has a very broad development prospects.