The machine vision industrial inspection system is divided into two categories, quantitative and qualitative, in terms of its detection properties and application range. Each class is divided into different sub-categories. Machine vision is very active in various applications in industrial online inspection, such as: visual inspection of printed circuit boards, automatic flaw detection of steel sheet surfaces, parallelism and perpendicularity measurement of large workpieces, container volume or impurity detection, automatic identification and classification of mechanical parts. Geometric dimension measurement, etc. In addition, machine vision systems can be effectively implemented where many other methods are difficult to detect. The application of machine vision is increasingly replacing people to do a lot of work, which undoubtedly greatly improves the level of production automation and the intelligence level of the detection system.
Application examples of machine vision in quality inspection
Machine vision systems are widely used in various aspects of quality inspection, such as large workpiece parallelism and perpendicularity measuring instruments using laser scanning and CCD detection systems. They use a stable collimated laser beam as the measurement baseline, with back The rotating shaft system rotates the pentagonal prism to sweep out the parallel or vertical reference planes and compare them with the faces of the large workpiece to be tested. When processing or installing large workpieces, the discriminator can be used to measure the parallelism and perpendicularity between the faces.
The stroboscopic flash is used as the illumination source, and the area array and linear array CCD are used as the detector parts of the contour shape of the rebar to realize the dynamic detection system for the on-line measurement of the geometric parameters of hot-rolled rebar.
Visual technology monitors bearing load and temperature changes in real time, eliminating the risk of overload and overheating. Passive measurements that traditionally measure machining quality and safe operation by measuring the ball surface are turned into active monitoring.
Using microwave as the signal source, according to the square wave of the microwave generator emitting different wave rates, the crack on the metal surface is measured. The higher the frequency of the microwave wave, the narrower the measurable crack.
In short, there are many similar practical systems, which are not outlined here. Below we describe three practical machine vision systems in more detail.
Machine vision based dashboard assembly intelligent integration test system
EQ140-II automobile instrument panel assembly is a meter product produced by an automobile company in China. The instrument panel is equipped with speed odometer, water temperature meter, fuel gauge, ammeter, signal warning light, etc. The production batch is large and needs to be carried out once before leaving the factory. Final quality inspection. The detection items include: detecting the indication error of five meter hands such as the speedometer; detecting whether the 24 signal warning lamps and the plurality of illumination 9 lamps are damaged or missing. Generally, it is checked by manual visual inspection method, which has large error and poor reliability, and cannot meet the needs of automated production. The intelligent integrated test system based on machine vision has changed this situation, realized intelligent, automatic, high-precision and fast quality inspection of the instrument panel assembly, overcoming various errors caused by manual detection and greatly improving detection. effectiveness.
The whole system is divided into four parts: an integrated multi-channel standard signal source for analog signal source for the instrument panel, a two-coordinate CNC system with image information feedback positioning, a camera image acquisition system and a master-slave parallel processing system.
Metal plate surface automatic injury control system
The surface quality of metal plates, such as large power transformer coil flat wire radios, has high requirements, but the original method of manual visual inspection or centrifugal plus needle control is not only susceptible to subjective factors. And it may draw a new scratch on the surface being tested. The automatic flaw detection system on the surface of the metal plate uses machine vision technology to automatically inspect metal surface defects, and performs high-speed and accurate detection during the production process. At the same time, the use of non-angle measurement makes it possible to avoid new scratches. In this system, a laser is used as a light source, and the stray light around the laser beam is filtered by a pinhole filter. The beam expander and the collimator mirror convert the laser beam into parallel light and uniformly illuminate the inspection at an incident angle of 45 degrees. Metal plate surface. The metal plate is placed on the inspection table. The test bench can be moved in three directions: X, Y and Z. The camera adopts TCD142D type 2048 line Chen CCD, and the lens adopts ordinary camera lens. The CCD interface circuit uses a single chip system. The host PC mainly performs image pre-processing and classification of defects or depth calculation of scratches, etc., and can display the detected defects or scratch images on the display. The two-way communication between the CCD interface circuit and the PC through the RS-232 port, combined with the asynchronous A/D conversion mode, constitutes an interactive data acquisition and processing of the human-machine.
The system mainly uses the self-scanning characteristic of the linear CCD in combination with the movement of the inspected steel sheet in the X direction to obtain three-dimensional image information on the surface of the metal plate.
Germanium Plano-Convex (PCX) Lenses feature precision diamond turned surfaces making them ideal for a variety of infrared applications, including thermal imaging, infrared spectroscopy, and remote sensing. Germanium (Ge) is popular for its high index of refraction, broad transmission range, and rugged mechanical properties. These lenses are available in 25 and 50mm diameters, uncoated, or with multiple broadband coating options.
Germanium (Ge) material feature high index of refraction (around 4.0 from 2 - 14μm), an anti-reflection coating is recommended on these germanium windows for sufficient transmission in the region of interest. Germanium is subject to thermal runaway, meaning that the transmission decreases as temperature increases. As such, these germanium windows should be used at temperatures below 100°C. Germanium`s high density (5.33 g/cm3) should be considered when designing for weight-sensitive systems. 
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Germanium windows specifications |
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| Standard precision | High-precision | |
| Dimension Tolerance | φ5-250mm+0/-0.2 | φ3-350mm+0/-0.2 |
| Thickness Tolerance | 1-50mm+/-0.1 | 1-50mm |
| Parallelism | 1 arc minute | 10 arc seconds |
| Surface Quality | 60/40 | 20/10 |
| Flatness | N<λ/2@633nm(at 50mm) | N<λ/10@633nm(at 50mm) |
| Clear Aperture | >90% | >95% |
| Chamfer | Protected <0.5mmx45deg | Protected <0.5mmx45deg |
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China Star Optics Technology Co.,Ltd. , https://www.opticsrealpoo.com