Research On Thermal Error Compensation For RAM Components Of NC Heavy Type Milling-Boring Machine Tool With Adjustable Stand

Ram components are essential components of NC heavy type milling-boring machine tool with adjustable stand, which is an important equipment in the pillar industries such as national defense industry, arms industry, transportation, and engineering machinery, etc. Ram components directly determine the process accuracy of a machine tool. During the process of using NC heavy type milling-boring machine tool with adjustable stand, ram components are jointly affected by internal and external heat sources which raise the temperature of ram components, result in the thermal deformation of them, and consequently impact the process accuracy of a machine tool. This thesis is aimed at a thermal analysis of the ram components of NC heavy type milling-boring machine tool with adjustable stand. A scheme to solve the problem is proposed in this thesis and an experimental demonstration is provided. The work of this thesis mainly includes:The factors influencing the thermal characteristics of the ram components are ascertained according to their structural characteristics. The formation of thermal errors in the W axis of the tool is analyzed in different patterns of feedback control.According to the actual working conditions, the heat sources and boundary conditions of the ram components are counted; the finite element model of ram components are built; the temperature field and the thermal deformation field of ram components are analyzed, and thus the proportion of thermal errors is obtained; the relationship between the influencing factors and the thermal deformation of ram components are obtained by analyzing the finite element model under different boundary conditions.The position of the ram in the W axis of the tool and the influence exerted by the rotate speed of the spindle on the thermal deformation of ram components are obtained according to the measurement and analysis of the temperature of the key point and the deformation of ram components; by comparing the thermal deformation of ram components gained in this experiment and the thermal deformation gained in the finite element modeling, the accuracy and the credibility of the finite element model of ram components is tested.According to the formation of the thermal errors, the ram in the fore-end of the nut is thermally deformed; the scheme to detect thermal deformation and the remedial measures are proposed; with regard to the thermal errors caused by the thermal deformation of the grating bar, a scheme to install and improve the grating bar of the ram is proposed. With the finite element method, the scheme to detect the thermal deformation of the ram and the scheme to install and improve the grating bar of the ram are analyzed to test the feasibility and accuracy of the scheme. The result of the test demonstrates that the deformation of the ram can be accurately detected with the scheme. A compensating device is developed for the deformation of the ram in the fore-end of the nut. The experiment demonstrates that the NC machine can accurately receive the control pulse sent by the compensating device.