Progress of the hottest industrial endoscope

2022-09-22
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The progress of industrial endoscope

the basis of nondestructive testing technology is to see what the naked eye cannot see. Ultrasonic waves are used to identify defects and corrosion in metals, especially at welds. Radiographic techniques can be used to inspect castings and inclusions for tubes, laminations, or other defects. Eddy current can be used to detect hidden cracks on layered surfaces. Industrial endoscope (RVI) is widely used in aerospace industry to inspect aircraft components and structures, from engine to fuselage. In recent years, RVI has made great improvements in imaging and technical measurement capabilities, which will be described in detail in this paper

in the aviation field, industrial endoscope (RVI) is an inspection and nondestructive testing technology with a long history. Although the traditional rigid rod endoscope is still widely used in aircraft engine detection, video endoscope has become the first choice, which can be used in military and civil fields to check the fuselage, auxiliary power devices and engines. These are regarded as routine maintenance activities. To be precise, the minimum dimension is to consider the improvement of oil function by some oil additive. The inch should not be greater than a part of mm. Original equipment manufacturers also use video endoscopes when manufacturing engines. Use video endoscope to check leakage, corrosion and surface cracks, check internal cracks, identify the cause of blockage, and detect external objects. It is understood that video endoscope has such a wide range of potential applications that video tape has realized the capture and preservation of digital data. This technology has been further developed into CD, DVD, flash memory and solid-state memory card, which can transfer files to PC for further evaluation or storage

Evolution of RVI

Industrial endoscopy originated in the medical industry. In 1806, the Austrian developed the first endoscope for the examination of human blood vessels and body cavities

after World War II, the development of industrial endoscope was getting better and better. The early instruments were composed of lens and lighting source, which were connected to a light transmission expander, namely eyepiece. These basic endoscopes are only used for visual inspection, not measurement. In this way, people use it to detect locations that are inaccessible or inaccessible under normal conditions due to the obstruction of structures or components

until the 1960s, industrial endoscopes had the ability of image capture and measurement. At this time, 35mm cameras added eyepieces. Along with it, optical fiber is introduced into the optical transmission mechanism, and video lens has become the first choice of image capture. At the same time, with the introduction of airborne computing power, the function of video endoscope has been significantly improved, which enables the endoscope to save and store video images in digital format. Previously, the sharing of floppy disks and testing information was an important part of any testing process, especially in the aviation field. For safety and economic considerations, professional evaluation of the normal operation of the engine was often required. Therefore, the function of sharing information is unique to the latest generation of RVI instruments

process data

implant the airborne PC into RVI, that is, introduce application software, so as to ensure the effective management of a large number of generated data. Such software can mark images and arrange them in the form of logical files, allowing fast and simple reading. Xlg3, launched by GE testing control technology, uses the digital imaging and communication (DICONDE) format in nondestructive testing. It is a non proprietary format, developed from DICOM used in radiology in the medical industry, and incorporates many pure nondestructive testing features

this agreement forms the basis of Ge rhythms software platform, which can obtain, report, audit and archive data. It is also an important application tool, including image enhancement, manipulation and zoom

the aviation industry often has to deal with an increasing number of detection information, and the archive feature is particularly closely related to it. It accepts images from arbitrarily connected local and remote rhythmreview workstations and uses various compression technologies to save them, saving memory space without sacrificing image quality. DICONDE's simple marking system makes information input and retrieval fast and convenient. Moreover, rhythm archive not only stores raw material detection data, but also stores enhanced images generated by rhythm review workstation. In addition, it also brings other benefits to users. It can search more effective data, because it can be stored in the center to better realize the man-machine running in device to get all the information of all workstations in the same network. It can also control the flow of image information, so the data can be sent to other rhythmview workstations for further analysis

cursor positioning in phase detection

simplification

software can also be used to standardize the detection program to ensure the consistency of detection and detection result description. Menu based detection wizard (MDI) is a software solution that provides guided detection and automatically adds environments. For example, when testing the engine, the drop-down menu will first let the tester select the relevant manufacturer and specific engine. Before the tester starts the test, input all the certification data related to the task (tester, location, date, etc.) in the way specified by the corresponding engine or component. Then, in the data capture system of the endoscope, the data image file is marked with comments and fields. Finally, a hard disk copy of the report is generated. Click To report

measure what you see

now, the measurement of defects, differences and gaps is as important as their detection and identification. So far, there are three main measurement systems: comparative measurement, stereo measurement and shadow measurement

comparative measurement is to measure other objects with the same view and plane based on a known reference size in the detection image (the reference size is often set in the appropriate place by the instrument manufacturer, or determined by using a probe)

stereoscopic measurement uses prisms to segment images, allowing the camera to capture the views of the left and right using accurate angle separation, and then uses computer algorithms to analyze the position of the user cursor. Anqing new chemical materials industrial base adjusts the future plan in time in combination with Anqing's actual situation, and uses trigonometric geometry to obtain precise measurement results

shadow measurement depends on the measurement of the distance to the target. The shadow lens projects on the detected object, and the shadow position generated shows the distance to the object. With this information, the shadow probe system can accurately calculate the size of the defect selected by the user. These methods can measure depth, length, area, point to line distance, length of multiple line segments, and circle

phase measurement can improve imaging and make measurement more accurate

although there are various measurement technologies at present, measurement is still the most thorny problem of video endoscope. The inspectors must be well-trained and experienced, so as to obtain stable, reliable and repeatedly verifiable results. This level of expertise is now known as RVI, which is a professional official NDT standard and a part of the testing and certification process of American Nondestructive Testing Association tc1alevel-iii

recently, with the development of phase measurement methods, the accuracy, repeatability and ease of use of video endoscopes have been greatly improved

three dimensional phase measurement is a technology based on existing optical metrology. It projects linear light onto the surface, captures this linear pattern with a camera with high-quality optics, and then processes the image with a proprietary algorithm to obtain a three-dimensional point cloud image of the entire surface. Then it is combined with measurement to obtain more accurate information about defects or tested objects. The measurement itself only includes the placement of the cursor on the full screen image, and does not require point matching, shadow identification or point selection. These steps are difficult to implement with other technologies

a major innovation of the measurement system is the 3D scanning with rotation and scaling functions, which provides a strong indication of the size and shape of objects. The section view features of the system provide further help for the estimation of object size and shape. When the user places the cursor on either side of the region of interest, the three-dimensional phase measurement system will draw a line between the two sides. Then select the section view, and the intersection along this line will be displayed to make the depression, crack or corrosion more clear. At the same time, the section view can also be used to measure the depth of some points in the section

improve productivity through greater ease of use

measurement methods using stereo and shadow are time-consuming and require expertise. For example, using stereoscopic measurement, we must first use the observation lens to identify defects, then replace it with stereoscopic measurement lens, and then reposition the defects, lock the image, match the cursor, and finally measure. Using the phase measurement method, once the defect is located and the image is locked, the measurement can be started without changing the lens

because there is no need to carry out such steps as point matching, shadow recognition, cursor matching or point selection required by other measurement technologies, 3D phase measurement method shows great ease of use. This means less operational errors and more accurate results that can be verified repeatedly

more potential applications

an important application of three-dimensional phase measurement technology is to measure the gap between the top of aircraft engine and the shield

the unique design of aircraft engines and other shaft turbines can reduce the diameter distance from blade tip to blade or shell. If there is a gap between the tip and the shell, gasoline or air may leak into the downstream part, resulting in reduced efficiency. Therefore, whether in the process of production or maintenance, it is very important to check the clearance, because the size of the clearance will change when the engine is working (high speed and high temperature will lead to the growth of the elastic diameter of the blade and the thermal expansion of the shell)

in order to measure the gap between the blade tip and the shell, a thin metal rod can be inserted into the shaft bolt, and then this fitting can be connected to the bellows, so that the end of the metal rod is exactly where the blade tip is located. After the engine is started, the wear of metal rods can be measured. Obviously, this is not a high-precision technology, and it often causes problems. For example, metal rods will release metal, which may cause damage to the engine

phase measurement method provides a simple, non-contact and high-precision technology to measure the clearance from blade tip to shell

conclusion

industrial endoscopy has shown many advantages since its birth. Due to the full digital data stream and improved optical lighting technology, the imaging quality has been significantly improved. The integration of airborne processing greatly expands the functions of RVI and greatly promotes data sharing through network connectivity. Application software (such as MDI) helps to improve the success rate of detection and reduce the occurrence of detection errors. The software platform for collecting, checking, reporting and archiving complex data can effectively organize the accumulated data to achieve the best results. Now this innovative RVI measurement technology is easy to realize, can provide fast and accurate results, and has more comprehensive imaging information, which improves the quality control level of the production process and makes the detection more intelligent and effective. (end)

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