I. The development process of laser marking:
The core of laser marking machine is control system and marking head. Therefore, they are constantly updated and progressed with the development of laser marking machines.
Since 1995, the field of laser marking machines has experienced the large-format era, the rotating mirror era, and the galvanometer era, its control mode also completed a series of evolution from software direct control to control of the upper and lower machines to real-time processing and time-division multiplexing. Nowadays, the emergence and development of semiconductor laser machines, fiber laser machines, and even uv laser machines pose new challenges to optical process control ------ the galvanometer-type laser marking head (galvanometric scanning system) is the latest product.
In 1998, large-scale application galvanometer scanning system in China began to come. The galvanometer, also known as ammeter, whose design idea completely follows the design method of the ammeter, the lens replaces the hands, and the signal of the probe is replaced by a computer-controlled DC signal of -5V—﹢5V or -10V—﹢10V to complete the predetermined action. Similar to the rotating mirror system, this typical control system uses a pair of foldback mirrors. The difference is that the stepper motor that drives this lens is replaced by a servo motor. In this control system, the use of position sensors and negative feedback loop design ideas to further ensure the accuracy of the system, the entire system scan speed and repeat positioning accuracy is up to a new level.
II. Laser scanning principle:
The galvanometer scanning marking head is mainly composed of an XY scanning mirror, a field lens, a galvanometer, and a computer-controlled marking software. The working principle is that the laser beam is incident on two mirrors (scanning mirrors), and the reflection angle of the mirror is controlled by a computer, the two mirrors can be scanned along the X and Y axes respectively, so as to achieve the deflection of the laser beam, so that the laser power spot with a certain power density moves on the marking material as required, leaving a permanent mark on the surface of the material, and the focused spot can be round or rectangular. The scanning mirror provided by the Wuhan Division of Nanjing Wavelength Optoelectronic Technology Co., Ltd. has a reflectance of 99.5% or more, and the size of each sheet is calculated based on the size of the laser beam. Compared to two-axis scanning mirrors, Y-mirrors generally have a larger size than X-mirrors, X-mirrors scan to Y-mirrors rather than directly to the object.
In the galvanometer scanning system, the vector graphics and text can be used. This method uses the graphics software of the computer to process the graphics, has the characteristics of high efficiency, good graphic accuracy and no distortion, which greatly improves the quality and speed of the laser marking machine. At the same time, the galvanometer marking can also adopt the dot matrix marking method, which is very suitable for on-line marking. According to different speeds of the production line, one scanning galvanometer or two scanning galvanometers can be used. Compared with the array marking described above, more dot matrix information can be marked, which has greater advantages for marking Chinese characters.
Galvanometer scanning marking machine has become a mainstream product because of the advantages of wide range of applications, can apply for vector marking and dot matrix marking, adjustable marking range, fast response speed, high marking speed, high marking quality, good optical path sealing performance, and strong adaptability to the environment. It is considered to represent the future development direction of laser marking machines and has broad application prospects.
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