Study On Extrusion Mechanism Of Ceramic 3D Printer Based On Micro-flow Extrusion Forming Process

Ceramic materials are widely used in machinery,aerospace,electronics,biomedicine and other fields due to their characteristics of high temperature and corrosion resistance and high hardness.Traditional ceramic manufacturing process has many disadvantages which is unable to meet the increasing demand of ceramic products and the huge market,such as high manufacturing cost,long manufacturing cycle,low processing efficiency,poor manufacturing accuracy and raw material waste etc.With the development of science and technology,the new ceramic manufacturing technology additive manufacturing(AM)technology can make up for the defects of traditional technology.The micro-flow extrusion forming,which has drawn world-wide attention and research for its unique advantages,such as short cycle,suitable for ceramic parts with complex shape,high precision and low cost.However,there are still some problems such as low precision of extrusion system,unstable extrusion pressure,liquid phase migration and salivation of slurry,as a result,the forming effects decline.So,the extrusion system of micro-flow extrusion forming is focused on.The main researches were as follows:(1)The micro-flow extrusion process and its technical characteristics,the rheological properties of slurry and the main equipment of the process were analyzed.The advantages and disadvantages of three types of splunger,pneumatic and screw were compared with each other.According to the working principle and characteristics of the progressing cavity pump,the feasibility of the progressing cavity pump as the core conveying component of the microflow extrusion mechanism is theoretically analyzed.(2)The extrusion mechanism of micro progressing cavity pump was designed,and its working characteristics and working principle were studied.The extrusion head forming section model and micro progressing cavity pump section model were established.The results showed that the structural parameters of micro progressing cavity pump had great effects on extrusion flow,pressure and mechanical efficiency.Finally,the structural parameters of extrusion head and progressing cavity pump were designed.(3)The motion characteristics of the stator rotor are analyzed and the motion simulation,assembly simulation and finite element analysis are carried out.Two points were selected arbitrarily on the outer surface of the rotor,and the curves were analyzed including motion trajectory,displacement,velocity and acceleration.Results indicated that the trajectory of any point formed an ellipse,and the displacement,velocity as well as acceleration changed regularly and periodically.The finite element simulation was executed to analyze the stress and strain of the micro progressing cavity pump under uniform pressure,which proved the structural design to be correct,the operation law and the single-stage sealing ability to be good,providing a basis for further experimental research.(4)Micro-flow extrusion experiments were carried out.In this experiment,the range of inlet pressure of key parameters is obtained,and the relationship between rotational speed and actual flow rate is approximately proportional.Meanwhile,compared with the piston extrusion system,the micro progressing cavity pump showed much better characteristics such as stable pumping pressure and extrusion effect in liquid phase migration and salivation.Then,the reasons about above results were deeply discussed and could be proved by further experiments.