The Research On The NC Milling Method Of The Conical Twin-Screw

The conical twin-screw extruder which is applied to process PVC and UPVC has been developed rapidly and used widely with the development of plastic industry and the extensive use of PVC and UPVC in the past years. As the key part of extruder, the improvement of screw pushes the evolution of extruder. The processing parameter of milling decides the precision of screw, and influences the quality of product and the capacity of extruder, including conical twin-screw extruder. Currently there is still some theory gap in conical twin-screw processing methods; the literature and research on that are not as much as parallel twin-screw or single screw.This thesis focuses on the NC milling methods of conical twin-screw with straight outline gear form and the feasibility analysis of using countersinking vertical milling cutter to process conical twin-screw. Algorithms used to resolve the math problem met in the working process are researched and analyzed, including a series of the computation of the basic parameter of conical twin-screw and the cutter spacing during processing conical twin-screw. The computation was implemented with Borland C++ Builder 5.0, and a CAM system of conical twin-screw was developed. The system can automatically generate NC programs, transmit the programs to the spiral groove NC milling tool, which is developed by Shenyang University Technique and Development Co., Ltd., and use countersinking vertical milling cutter to realize the NC milling for conical twin-screw.The successful research on this subject promotes the processing technique of conical twin-screw in our country. It provides important theory proof and valuable test data and lays the foundation for further research on the processing method of conical twin-screw. It can be a guide for the production practice and provide a theory base for the research on the NC milling processing on other gear forms of conical twin-screw.