Study Of Key Techniques For The Automated Dynamic Paper Sheet Former

With the development of papermaking te chnology, more refinement is the main development direction of the advanced instruments and equipment in the paper industry. However, the sheet former is indispensable experimental equipment and also important limiting factor for many pulp and paper properties research. The main reason is the sheet structure difference between industrial and laboratory. That is to say, the traditional hand-sheet former cannot simulate the papermaking process forming conditions real, for example the dewatering and orientation shear when the sheet formed on wire. Meanwhile, low experimental repeatability and working efficiency also should not be neglected. In industry, the most common type s of paper machines are fourdrinier and twin-wire paper machines. And, due to wide range of application and good adaptability to the market, the fourdrinier machines are main model now and in the future. Therefore, to develop laboratory full-automated dynamic sheet former is nec essary, which simulate forming process of fourdrinier.This paper revolves the key technology research of the full-automatic dynamic sheet former, which includes simulation mechanism, design theory, structure, numerical simulation, structure optimization, experiment verification and so on. The main research work can be summarized as follows :1) Researched simulation of the papermaking process about the full-automated dynamic sheet former.Considering the main factors influencing the quality of sheet, the forming conditions of fourdrinier essence effect on fiber orientation and filler distribution was analyzed and researched. And obtained to simulate process of fourdrinier machine is pulp flow, sheet forming, and evaporation dry for the full-automated dynamic sheet former.2) Researched simulation mechanism and process about the full-automated dynamic sheet former.Based on the nature of the fiber orientation, according to the similarity theory, simulation mechanism of the dynamic sheet former was proposed. And then designing mechanism of flow channel of fiber suspension forming was suggested. Lastly, the technological process of the full-Automated dynamic sheet former was determined.3) Researched implementation theory and structure design about the full-automated dynamic sheet former.By fluid dynamics and statics knowledge, aimed at important and difficult inducted mathematically, design theory of the dynamic sheet former was obtained. For example, jet-wire speed difference, slurry forming dewatering, basis weight and fiber turbulent. Through the Solid Works software, the three-dimensional structure of the key parts of the full-automated dynamic sheet former was designed.4) Researched structure of the forming tank by numerical simulation method and verified the forming performance of the forming section by experimental about the full-automated dynamic sheet former.Used ANSYS-CFX software, established three-dimensional simulation model, adopted the gas-liquid two phase flow unsteady numerical simulation method analyzed the fiber slurry flow characteristics in the forming stank. D esign theory of the forming tank was verified, and structure of the forming tank was optimized. And then experimental device of forming department was design and build. Through experiment, sheet structure and performance was measured, such as thickness distribution and fiber orientation arrangement. It was verified that the dynamic sheet former simulated forming mechanism of fourdrinier machine. At the same time, it were analyzed that dewatering vacuum is the main factor to affect uniform region of the sheet.