Research On Plastic Additive Manufacturing System Based On Needle-type Droplet Jetting Technology

In recent years,3D printing technology had attracted much attention at home and abroad, and corresponding processing technology emerge in endlessly. Main research thought is based on the discrete-integral increase material manufacturing technology. With the development of processing materials tend to be multidirectional, the material manufacturing process technology is more flexible and applied in various industries. But the real large-scale industrial production need a long period of time, despite the increasing processing material, but its intensity and industrialization is hard to meet the industrial requirements. The additive manufacturing based on needle-type droplet jetting technology has the advantages of low-cost and easy operation, etc. At present, difficulty coefficient of the high viscosity polymer for jet machining is very large, especially for general plastic, processing raw materials of 3D printing technology still need further research and development. In this paper, the polymer micro droplet jetting increase material manufacturing technology of basic research is an important supplement in this area.1. The polymer in this article has the advantage with high melting point, So the needle-type injection technology on the injection molding was adopted. The detailed theoretical analysis of molten droplets of polymer injection process has carried on. The emphasis is on establishing the melt fracture theory model, to obtain high polymer melt jet velocity of critical point and to summarize the initial conditions of droplet jetting.2. Bond graph modeling theory has been used to study the nozzle inside the polymer melt flow characteristics and melt polymer injection process, the influence of micro droplet injection speed, a single droplet size and droplet solidification after the shape of the main parameters are obtained:nozzle structure, nozzle diameter, melt pressure, driving pulse frequency, pulse width, etc. And the meshless numerical simulation software for the whole process of the nozzle jetting was used. The simulation result shows that in the whole process of the melt jetting, the role of the needle is outstanding, and the smaller the nozzle diameter, the jet velocity is greater, the single droplet size is smaller.3. The dynamic characteristics of the system was analyzed, the characteristics of displacement and velocity of the needle was studied in the process of micro droplet jetting, and the needle-type droplet jetting forming system was integration designed based on the theory of droplet jetting technology. This paper also provides an experimental platform for the study of the mechanism of micro droplet jetting forming and processing technology research.4. Droplet jetting molding experiment was conducted to system of micro droplet jetting experiment and three-dimensional parts were finished. The parameters of a single droplet average volume and shape after solidification were studied. The experimental results show that the influence of melt pressure on single droplet volume was important. The mathematical relationship between the two is roughly proportional relationship. We also found that a single droplet volume increased with the pulse width. And the pulse frequency mainly affected the shape of the droplet after solidification, such as the angle between the droplets and base plate, the height of the droplets and droplet diameter, etc. With the drive pulse frequency increased, the angle between the droplets and base plate is smaller and the droplet height is smaller, but the volume and quality of the droplet remain the same. At last, the impact performance test of 3D printing parts was conducted to provide a method to measure of this kind of 3D printing parts mechanical performance.