Study On Cutting Performance And Design Optimization Of Cutting Tool For Machining Water Chamber Head Material

AP1000 nuclear power unit is widely used in China's nuclear power plant.The evaporator water chamber head is the main part of the unit.Its material is 508 III steel,which is difficult to machine.It has high hardness,plasticity and strength.Heavy cutting,as its main processing method,belongs to typical extreme manufacturing.The cutting parameters of water chamber head are much larger than that of common cutting(cutting speed is generally 300-400 m/min,feed speed is 1-1.2 m/min,cutting depth can be more than 4 mm).The tool bears large cyclic impact load in the process of machining,which leads to serious tool damage and failure.At the same time,due to the large removal margin,more surface defects and lower processing efficiency of forging water chamber head blank milling.In view of the above problems,this paper studies the structural design optimization,finite element analysis and cutting performance evaluation,and carries out the cutting performance analysis and design optimization of the water chamber head material processing tool,which has important theoretical value and significance for the development of heavy cutting tool.Firstly,the processing characteristics of heavy-duty cutting process are analyzed from the aspects of structure,material and processing technology of water chamber head;cutting force and heat are studied by combining milling experiment and simulation respectively;the influence of load characteristics on tool material damage in heavy-duty cutting process is discussed,which provides a theoretical basis for the research of cemented carbide tool failure behavior.Secondly,through the combination of theory,experiment and simulation,cutting experiments are carried out with different materials,structures and coatings to analyze the anti-damage performance of different blades.At the same time,thermal-mechanical impact load analysis is carried out on the cutting area of the blade by using finite element analysis method.According to the damage mechanism of heavy milling cutter for water chamber head,damage model and life prediction model are combined.The matching principle of material-structure-coating for heavy-duty and high-efficiency cutting inserts is proposed.Thirdly,the optimization and analysis of cutting tool design for water chamber head material processing are carried out.The feasibility of application of layer-cut milling cutter is analyzed by comparing experiments.Aiming at the large machining allowance of hard-to-machine material 508 III steel,the structure of carbide cutting tool is designed.The cutting parameter optimization model is established with the goal of optimum machining efficiency and tool life.The cutting parameters of genetic algorithm are compiled by using MATLAB software.The optimum parameters are obtained by optimizing the program,and the tool structure is designed according to the cutting parameters.Finally,the cutting performance of the optimized cemented carbide cutter is evaluated.Based on the experimental results,the evaluation index is selected,and the comprehensive fuzzy evaluation is carried out based on the theory of fuzzy mathematics,which provides technical support for heavy efficient cutting and improving the processing quality and tool life.