Experimental And Theoretical Research On The Melting Process Of The Plasticizing Unit Of Disc Injection Molding

With the continuous development of micro-nano manufacturing technology,as an important direction of micro-nano manufacturing technology,micro-injection products are used in more and more fields,the disc injection molding machine has been developed as a new type of micro injection molding machine with high precision and high speed,suitable for micro-nano products,as the key part of the plasticizing unit of the disc injection molding machine,the melting property of the grinding disc plays a decisive role in the quality of the products.At present,there is a lack of research on the melting and plasticizing mechanism of the disc injection molding machine.It is of great significance to carry out experimental and theoretical research on the melting process of the plasticizing unit of the disc injection molding machine to optimize the design and molding process of the plasticizing unit of the disc injection molding machine and obtain higher quality micro-injection products.In this paper,through the experimental study on the melting and plasticizing process of the plasticizing unit of the disc injection molding machine,the influences of the structures and process parameters of the grinding disc on the melting and plasticizing were explored.The physical and mathematical models of the rotating and stopping stages of the grinding disc were established and the numerical simulation of the melting process was carried out by using MATLAB.The main work completed is as follows:(1)The melting and plasticizing process of the disc injection molding machine was studied experimentally by using two different structures of the grinding discs,the molten state of high-density polyethylene material in the grinding disc of the disc injection molding machine was observed,and the changes of the width of the molten pool along the conveying direction of the material in the screw groove of the grinding disc was observed.The influences of temperatures of the fixed plate,rotational speeds of the rotating plate,clearances between the rotating plate and the fixed plate and stopping time of the rotating plate on the melting process of the material in the grinding disc were explored,and the melting and plasticizing mechanism of the disc injection molding machine was analyzed.(2)Based on the experimental results of the disc injection molding machine,the melting process of the material in the grinding disc was divided into the melting delay section and the melting section,and the physical models of the melting process of the material in the screw groove during the rotating stage of the grinding disc were established.The governing equations of mass,momentum,pressure and temperature and the interface equilibrium equations of the infinitesimal elements were obtained by means of the infinitesimal analysis method.The boundary conditions and initial conditions were established,and the solving process was discussed.(3)According to the results of melting and plasticization experiments,the physical models of the melting delay section and the melting section of the grinding disc were established and analyzed.Based on the physical models,the heat conduction equations and interface equilibrium equations of the solid bed and molten film in the melting delay section as well as the solid bed,molten film and molten pool in the melting section were established by using the infinitesimal analysis method.The boundary conditions and initial conditions were determined,and the solution process was discussed.(4)Based on the established mathematical models,the finite difference method was used to numerically simulate the melting process of the grinding disc during the rotating and stopping stages by using MATLAB software.The parameters of solid bed conveying speed,melting rate,molten film flow rate and the width of the molten pool and etc in the melting process were obtained.The influences of the rotational speed of the rotating plate and the width of the screw groove on the solid bed conveying speed,melting rate,molten film flow rate and the width of the molten pool in the melting delay section and the melting section were studied and analyzed.