Research On Theory Of Droplet Jet Generator And Application In Big Character Printing

Application of droplet jet technology began from inkjet printing field, and then extended to the industrial areas of packaging, chemicals, and even extends to rapid prototyping, micro-mechanical, optical device fabrication and materials science. There is not scientific research in the droplet jet generator with high flow and high-frequency response, which is used in big characters printing. The theory, design methods, and application in large characters printing of droplet jet generator were studied in this article which was supported by "research and development of big character high-speed dot-matrix Printing System" project of Zhejiang University Jingyi Electromechanical Technology Engineering Co., Ltd., in conjunction with the actual needs of the Tianjin Pipe (Group) Co., Ltd.. The main contents are as follows.In the first chapter, the significance of the research was stated in the steel industry as the main application background with the development and lack of code printing. The importance and necessary of research in these products was demonstrated through analysis of research status and classification of droplet jet generator. The ideas for research and development of droplet jet generator applied in large character printing system were proposed. And the related theories were introduced. The main research content and topic source were stated.The second chapter, on the basis of researching droplet jet generator structure and working principle, the process of droplet impact on a solid surface and forming points was scientific analyzed. Mathematical model of droplet jet control valve was built, and the characteristics of droplet jet control valve were studied. Theoretical support was supported to the design of droplet jet control of generator by creating a droplet jet control valve thermodynamic model, and analyzing the variation of the surface temperature of the coil.The third chapter, the composition and working principle of the system was analyzed on the basis the performance requirements of big characters printing system. The principle and process of forming the dot-matrix character were scientific discussed. The character encoding scheme was designed; the methods of adjusting the font and error compensation were proposed. With steel pipe automatic production line as the application background, the parameter calculation and structural design of the droplet jet control valve were performed.The fourth chapter, based on the analysis of variable structure control principle, the droplet jet control valve sliding mode observer was designed to observe the parameters of displacement and velocity in droplet jet control valve system; and as a basis, sensorless control strategies based on sliding mode observer was further proposed to make the spool displacement track ideal curve pre-designed without increasing any sensor, to reduce collisions and eliminate vibration. Simulation results verified the effectiveness of the control strategy.The fifth chapter, based on describing the causes for the chattering of sliding mode control and harm to the system, the principle of saturation function method, the smooth function method, reaching law method and other methods to eliminate chattering was analyzed. And further tracking system chattering suppression strategies were discussed. The simulation proved the chattering suppression strategy effectively suppressed chattering in spool tracking control process.The sixth chapter, by droplet jet control valve testing experiments, the correctness of the system model, the validity of sensorless sliding mode observer were verified. Furthermore, it proved that sensorless control strategies based on sliding mode observer could effectively eliminate the valve noise and vibration to improve printing effect. Experimental analysis of the effects of the parameters such as system pressure, valve travel on the pulse jet flow was provided for adjusting the printing result. The actual production test showed that the design of droplet jet generator in this paper fully meet the big character printing requirement in the pipe production line.The seventh chapter, the main research content and innovation in paper were summarized, and further research work is put forward.