Lithium Extrusion Molding And Pneumatic Cutting And Conveying Technology And Equipment Research

This project is the design of a miniaturised,efficient and highly accurate extrusion cutting and injection device.The purpose of the device is to form irregular lithium blocks into small sized lithium projectile pellets and eject them into the reactor.The whole process is carried out in a sealed chamber protected by argon gas and requires operations such as picking up,adding material,then precise extrusion and forming from the head by means of screw or plunger extrusion,pneumatic cutting and high pressure ejection to achieve precision forming and pneumatic cutting of a series of target materials.The whole process requires the coordination and cooperation of different units,difficult material processing,high output fluctuations in the extrusion system and the need for precise coordination with the pneumatic cutting head,which is difficult.The main elements of this subject include:(1)Based on the basic theories of polymer rheology and metal material rheology,the similarities and differences between lithium metal materials and general polymers at the stage division and theoretical level in single-screw extrusion processing are compared and analyzed.It is determined that the solid plug stable force ratio is the main factor to propel the extrusion of molten lithium,and it is pointed out that the biggest resistance to the single-screw extrusion processing of lithium is the additional pressure caused by its surface tension at the head.Numerical simulations are carried out for the key part of the extrusion process of lithium metal materials(i.e.the melt transport section)to provide theoretical guidance for the production practice of single-screw extrusion of lithium metal,and the most suitable screw configuration is determined to be a single-headed isodepth variable pitch screw.(2)Based on the basic theories of mechanics of materials and extrusion,the mechanical properties and pressure processing properties of lithium metal in different temperature ranges below the melting point are analysed,the temperature and extrusion speed are determined to be the main factors affecting the plunger extrusion process of lithium metal materials,the concept of crosssectional extrusion ratio is innovatively proposed,and the influence of the wear scale of the plunger extrusion pad on the extrusion process is analysed.Numerical simulations are carried out for the key aspects of the extrusion process of lithium metal materials,and the trends of the lithium metal properties are predicted to provide theoretical guidance for the extrusion of lithium metal plungers,and a more reasonable combination of process parameters is formed.(3)In response to the functional requirements of the device,the device is divided into five units: screw extrusion,plunger extrusion,environmental protection,pneumatic cutting and monitoring and control,and a detailed design is carried out for each unit.The key control parameters of the whole device system are analysed,and the influence of structural and process parameters on the stable extrusion and simultaneous and precise cutting of the device material is studied according to the input technical conditions of the subject,and the equilibrium relationship between the units is established.(4)A prototype of the device was completed and validation experiments were carried out with good results.The technical feasibility of screw extrusion moulding in a normal air environment was verified using metallic tin,the complexity and feasibility of the screw extrusion process and control in an argon protected environment was verified using metallic lithium and the feasibility of plunger extrusion moulding was verified using metallic lithium.Experiments were carried out on the cutting and injection performance of the device and the fit with the extrusion molding system and the results were generally in line with the requirements.The validation experiments of the device were overall as expected and met the acceptance criteria.