Research On Digitalized Robotic Plasma Cutting System And Process For Medium And Heavy Plate

In recent years, the proportion of medium and heavy plate in the steel industry applications increased year by year. In 2015, medium and heavy plate production has reached 130 million tons, which is mainly used in bridges, ships, aviation and other areas. Therefore, medium and heavy plate thermal cutting system with high quality, efficient and low-cost is urgently needed. In the field of thermal cutting for medium and heavy plate, plasma cutting owns prospect of being widely applied, which has the highest technical and economic nature. At this stage, high-power plasma cutting power supply has poor stability and control accuracy, low degree of digitization and integration, which is the key factor that limits it's the wide application in the cutting of medium and heavy plate. Therefore, it has important theoretical and practical significance to carry research on digitalized robotic plasma cutting system and process for medium and heavy plate.With the support of Science and technology project of Guangdong Province(Project number:2013B010402007) and Guangdong Province new generation CNC machinery product innovation demonstration project of special funds project(Project number: 2013B011302006), and in view of the problems existed in the cutting of the medium and heavy plate, this paper designed and developed digitalized robotic plasma cutting system with a set of stability, process, system by combining robotics and digital control technology. Firstly, it described and analyzed the status and trend of research on plasma cutting equipment and technology. In view of process considerations of plasma cutting for medium and heavy plate, this paper completed the overall design of digitalized robotic plasma cutting system. The cutting system includes digitalized cutting power supply, control section of water, electric and robot. The design of digital plasma cutting power supply mainly includes a three-phase EMI filter, the main power circuit, high-frequency arcing module. Peripheral control circuitry of Hardware circuit design is built on the base of the core of STM32F405RGT6, mainly including the smallest system of MCU, control circuit, fault diagnosis circuit, communication and isolation circuit. Software design of Cutting System with FreeRTOS real-time kernel programming environment, based on MDK-ARM platform, mainly includes the main program of control system, the soft-start program of current, the program of digitalized sharing current, the protection program of system fault, the program of communication. Finally, on the experimental platform of digitalized robotic plasma cutting system, output waveform and current soft-start, current sharing and efficiency, simulated arcing test and other tests are carried out under simulated load and the actual cutting conditions. A large number of low-carbon medium and heavy plate process experiments is carried out by varying parameters of the PID, gas pressure, cutting current, cutting speed, nozzle diameter and others, collecting experimental waveforms and data with oscilloscope and digital clamp table test instruments, and analyzing the formation of experimental result with different parameters.Through the above experiments, we can draw a conclusion that the design of the plate digitalized robotic plasma cutting system has advantages, such as good stability of starting, high precision of controlling, high level of digitalization. Achieving good process performance by combining robotic control, such as flatness, slope angle and dross of cutting kerf reaching the standards of laser cutting, which even further validates the feasibility and correctness of the design.