Research On Both The High-Efficiency Cuting Of Large Shell And The Tool Technology

The large shell blank is made by free forging, with the maximum diameter of above7m, the maximum height of6.4m and weight of over200tons. The processing condition of its forging surface is so worse. During its hogging machining, the material removal amount reaches50%and the cutting depth ap even reaches30mm. The high-temperature and high-strength steel2.25Cr-1Mo-0.25V is adopted as its material. During the cutting process, different cutting parameters will generate large chips with extremely high rigidity and various shapes. The fracture of the chips requires great mechanical load. Therefore, the fracture of the chips for each time will give rise to mechanical impact for the cutters. During the cutting process, the impact load (resulting from the forging defect and large chip fracture) and the hardened metal material of the work piece surface lead the hard alloy turning tool to generate impact breakage (impact fracture and fatigue fracture) and the occurrence of instability of mechanical properties under high temperature.Aiming at the generation feature of large saw-tooth chip, by the means of the integration of finite element simulation and cutting experiment study, it makes deep analysis on the features of heavy cutting, forms of large chip, and curling process, and reveals the generation mechanism of large chip by virtue of SEM observation; by the means of applying finite element simulation to analyze the curling process of large chip, it clarifies the scope of its fracture position, establishes a mechanical model of large chip fracture load, makes quantitative description towards its fracture load magnitude, analyzes the relevant factors influencing the accuracy of the model, and tests the accuracy and reliability of the model through cutting experiment.Aiming at the problem that the hard alloy turning tool easily generates impact fracture during the cutting, it applies mechanical impact theory, analyzes the causes of the impact fracture generation of the heavy hard alloy turning tool from the respective of impact load, and determines the critical condition for generating impact fracture; it adopts the method of integrating numeric description with the finite element simulation, analyzes and researches the generation mechanism and impact fracture form of the heavy hard alloy turning tool, and reveals the axial dimension rule of hard alloy shock strength through impact experiment.Aiming at the fatigue failure of heavy hard alloy turning tool, through fatigue experiment, it puts forward the generation mechanism of hard alloy fatigue fracture under dynamic load; through interrupted cutting experiment, it analyzes and researches the essential causes for the occurrence of fatigue behavior of hard alloy turning tool, and puts forward measures of preventing the early occurrence of fatigue.Aiming at the problem about the instability of mechanical properties of hard alloy turning tool resulting from high temperature during the heavy cutting process, it makes research on the generation and influence of the cutting heat. Through finite element simulative analysis, it reveals the generation mechanism of cutting heat during the heavy cutting process; through adopting temperature rise experiment, it analyzes the relation between the hard alloy hardness and the temperature variation, and makes research on the temperature variation effect of the hardness; through thermal shock and thermal expansion experiment, it makes research on the influence of thermal shock on the mechanical properties of hard alloy turning tool, and clarifies the maximum temperature range of the heavy cutting.It puts forward the cutting stroke calculation and impact lifespan evaluation method of the hogging machining procedure of large shell blank on the basis of image processing techniques, and clarifies the limit conditions of such method; it makes comprehensive analysis on the features of hogging machining of the shell, and puts forward the technological measures to realizing high-efficiency processing of the large shell.This paper adopts the hard alloy turning tool, and takes the cutting process of high-temperature and high-strength steel2.25Cr-1Mo-0.25V of heavy shell material as the research object. Through the methods of integrating theoretical analysis, numerical computational simulation with high-temperature performance test and cutting experiment, it makes research on the mechanics of large chip breaking, impact fracture, fatigue fracture, high-temperature mechanic features and lifespan evaluation of the hard alloy turning tool, etc. This research will provide theoretical guidance and technical support for the production synergy of the heavy cutting processing and the popularization of heavy turnin tool development technologies.