Parametric Design And Machining Accuracy Test Of Composite Damping Boring Bar

In deep-hole boring,the vibration of the boring bar affects the machining accuracy of the workpiece.Composite materials can improve the bending rigidity,increase the natural frequency and avoid resonance to the greatest extent.They are widely used in aerospace and military key parts processing fields.In this paper,the transverse vibration characteristics of laminar wound composite boring bar and the influence rule of vibration on the machining accuracy are discussed in depth by means of theoretical analysis,numerical simulation and experiment.The structure parameters of the boring bar are designed by orthogonal test and the influence of process parameters on the machining accuracy of the workpiece is studied by means of fuzzy mathematics.Through the research,the main innovative achievements are as follows.(1)The theoretical expression of equivalent bending stiffness of laminated composite boring bar under transverse isotropy is derived and verified by three-point bending test.The applicability of the theoretical expression is verified by the test results.(2)Based on the Euler-Bernoulli beam theory,the hyperstatic vibration model of the composite boring bar is established,and the partial differential vibration equation is solved by the independent variable method.The row and column expression of the characteristic value of the composite boring bar in the state of transverse free vibration and forced vibration is obtained.The solution of the determinant of the characteristic value is programmed,and the first four steps of the composite boring bar are obtained There are frequency and corresponding mode function,and the applicability of the method is verified by an example.(3)By using the finite element method,the steady-state relation of cutting force with time and position in boring process is obtained,and the influence of cutting force model parameters(rotational speed,feed rate,back cutting)on the transverse forced vibration of boring bar is simulated.(4)By using the workbench module of ANSYS,the three-dimensional finite element model of composite boring bar is established,and the influence rules of fiber volume ratio,fiber winding angle and fiber wall thickness on the vibration characteristics of composite boring bar are obtained.(5)The parameters of the fiber volume ratio,the fiber winding angle and the fiber wall thickness of the boring bar are obtained through the orthogonal test of three factors and four levels,aiming at the high natural frequency and the low end amplitude.(6)A cutting machining error measurement system for composite boring bar is designed,which is composed of ZK series deep hole boring machine,CSF-1A tension and compression sensor,BYES3600 CZ model roundness meter and SDY2107 A dynamic strain meter.(7)In this paper,a fuzzy mathematical model is established to predict the machining accuracy.With the cutting time as the constraint condition,the optimal values of parameters in the quantitative relations of workpiece roundness,straightness,roughness and back draft,feed and cutting speed are obtained by using Monte Carlo method.There are 60 figures,27 tables and 149 references in this paper.