Research On Manufacturing Of Nozzle

Nozzles manufacturing is one of the key technologies of localization and autonomy which needs to overcome for realize PWR fuel assembly design and manufacturing.The process of machining and welding is used in existing PWR fuel assembly nozzles,high processing cost and low efficiency.This project adopts the precision casting tube(casting)process processing,the internal structure of the water hole and the skirt of the nozzle can be directly cast,the appearance and all holes with high requirements are machined,the amount of material removal,the cutter type,the conversion cost are reduced effectively and the producing time is shorten,Specific research is carried out in the following aspects:(1)The research of producing wax,shell making of PWR was carried out,the main process and parameters of related process was determined.the surface quality problems of wax mould are solved by adjusting the temperature of liquid wax,the pressure and the time of wax injection,and the pressure holding time,conformed wax products were produced;the research of the slurry ratio,robot motion,sand sprinkling machine,drying temperature and drying time of shell making were carried out,important process parameters were determined.(2)the inspection of nozzle after casting were carried out.The corresponding inspection method of the X ray,permeability,dimension,chemical composition,grain size,corrosion resistance,mechanical performance test which meet the design requirements were established by experimenting.(3)the process research of nozzle after casting is carried out,the nozzle shape,chamfer,holes,center hole,positioning holes and other high requirement dimensions is machined by the CNC machining center equipment,special tool is designed for manufacturing the inner groove of holes according to the special groove back structure to meet the design requirements and accuracy;the processing scheme design for step hole and internal chamfer of center hole of the step drill integrated was adopt,the coaxiality of holes are ensured,and the processing efficiency can be effectively improved.After this project is researched,conformed top and bottom nozzles were manufactured,the precision casting,manufacturing,inspection of nozzles weremastered,production capacity of procession casting is possessed.The industrial of the nozzle of precision casting will be further promoted,the theoretical support and basis of precision casting industry will be provided for the full realization of fuel assembly nozzle for PWR.