Study On Design Method For Dynamics Of Machine Tools Considering Machine-tool-workpiece Process System

Machine tool is the basic unit of the manufacturing system, which aims to meetthe accuracy requirements of the components in accordance with the predeterminedcycle time. Therefore, the machining accuracy is the starting point and objectives ofthe research of the machine tool products. Under action of the incentives with cuttingload and unbalanced inertial load of the driving and implementing agencies, themachine tool is vibration, which could seriously damage the machining accuracy andreduce the processing efficiency. Therefore, the key to satisfy the machining accuracyis dynamic design to ensure the kinetic quality of the machine structure (vibrationresistance), control relative vibration within the allowed range between the tool andthe workpiece. Currently, due to the lack of effective dynamics design method, theaction of kinetic theory in machine design is limited in dynamic analysisand the finiteoptimization based on dynamic analysis, which is not successful to its efficacy. Forthe developing of machine precisionand the challenges of machine structure design,this paper proposes and studies the design method of dynamics of machine toolsconsidering machine-tool-workpiece system. The contents and contributions of thisthesis are as follows:1. The dynamic process with cutting load and unbalanced inertial load of thedriving and implementing agencies based on dynamics model of machine technologysystem is depicted. Quantitative analysis on the interaction of machine, tool andworkpiece in forced vibration is proposed. It makes that the relative amount ofvibration between the tool and workpiece in various dynamic force is controlledwithin the allowable range.2. Variable density method is introduced to discrete structure,and the dynamicsmodel of machine structural associated with the density distribution is establish.According to the dynamic model, the distribution of the structure quality of themachine tools is optimized via using the dynamics performance of machine tools asconstraint and the light mass and maximization of the first natural frequencies as thetarget, which gets the prototyping structure of machine tools.3. Parameterized model of the finite element analysis with the major componentsof gear shaping machineis established based on prototyping structure of machine tools.The critical parameters affecting dynamic performance of machine structure isextracted by sensitivity analysis of the dynamic performance in the quality and thenatural frequency. The critical parametersareused as the design variables of wholestructure optimization.4. Finite element analysis of YKW51250contrasts with the results of the experimental test in order to verify rationality of procedures and model of the finiteelement modeling.5. A parameterized model of the finite element analysis is established with thevariable parameters of key dimensions. Those variable parameters are used as designvariables of structure optimization of gear shaping machine, which are extracted bydynamic performance analysis. According to the size variables and test results, theapproximate model of response surface methodology with the natural frequency andthe mass of the key components of gear shaping machineis established. Design modelof multi-objective optimization of gear shaping machine is established, which uses thelight mass of machine structure and maximization of the first natural frequencies asthe target and upper and lower limit of the key variables of the host machine structureas constraint. The optimization model is solved to meet the host structural design ofgear shaping machine with high performance-price ratio.This thesis studies the design method for dynamics of machine tools consideringmachine-tool-workpiece system. Although the object of this thesis is gear shapingmachine, the ideas and principles of methodology proposed in the thesis areapplicable and general to the design of other manufacturing equipments.