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Electrolyte plasma polishing (EPP) is an innovative and efficient technology mainly used to polish complex metal products and obtain surfaces with low roughness and high gloss. However, limited by the electrolyte bath size, EPP method is not suitable for polishing workpieces with large size. This paper introduces a spray electrolyte plasma polishing (SEPP) method that can process large-scale and complex surface. The theoretical mechanism of SEPP is presented. GH3536 superalloy plates manufactured by SLM were used as the experimental specimens. The influence of cathode feed velocity on surface roughness is studied. Key parameters, like distance between anode and cathode, voltage, temperature, and flow rate of the electrolyte were investigated experimentally. Properties such as surface roughness, micro morphology, chemical composition, and surface hardness of the GH3536 specimens were detected and analyzed. The results show that SEPP technology can decrease the specimen surface roughness from Ra = 13.93 μm to 0.107 μm and obtain a smooth and glossy surface without obvious machining traces. The oxides and other impurities on the specimen surface were removed, and the contents of Ni, Cr, and Fe elements were increased. Additionally, the surface hardness values of the polished specimen were increased and showed good consistency. [ABSTRACT FROM AUTHOR]

The advantages of PBM (physically based model) over DDM (data-driven model) were presented, and physically based modeling of comprehensive thermal errors of servo axis and spindle was proposed. Based on the theory of frictional heat, heat convection, and heat conduction, the model for thermal error of servo axis was established, and the screw temperature field at any time can be obtained to predict screw thermal error. The thermal bending deformations of spindles were analyzed for a C-type vertical machining center. The models for spindle radial thermal drift error under different deformations were established, and the criterion for determining the deformations was presented. Tests for identifying parameters of the suggested models were carried out on a TC500R vertical machining center. The compensation effects were verified using both experiment and machining. The results indicated that the suggested PBM results in high accuracy and strong robustness, even if the moving state of servo axis and the rotating speed of spindle randomly changed. [ABSTRACT FROM AUTHOR]

Many studies indicate that thermal errors induced by spindle account for about 50-80 % of the total thermal errors of a machine tool due to the continuous rotation of the spindle during machining. The drawbacks of the commonly used axial thermal growth compensation methods for spindles were studied. In the present work, a robust axial thermal growth model for the spindle, based on the temperature variation, is proposed. Considering the exponential trend of the axial thermal growth of the spindle, the suggested model is based on an exponential formula. The results show that the steady value of axial thermal growth is changing with the spindle rotating speed. Therefore, the real-time steady value of axial thermal growth was predicted using the velocity and acceleration of temperature variation in the key point of the spindle. Additionally, the identification method for the parameters in the suggested model was also presented. The environmental temperature variation error (ETVE) and error induced by spindle rotation (EIBSR) were investigated using a CNC turning machine. The results recorded on the two turning machines indicated that high accuracy and strong robustness can be achieved with the suggested model, even when the rotating speed of the spindle changes randomly. [ABSTRACT FROM AUTHOR]

The disadvantages of the common thermal error compensation methods were analyzed. Based on the analysis, we report the concept of the comprehensive thermal error (CTE) of the servo axes of CNC machine tool. The total CTE was divided into the thermal expansion error (TEE) in the stroke range and the thermal drift error (TDE) of origin, and their sources and effects on workpieces were analyzed. Furthermore, models for TEE and TDE were established. The model for TEE derived from the heat production, conduction, and convection theory predicted the thermal field of a screw and the thermal errors of servo axes in real time. The model for TDE was established by the multiple linear regression method. The experiments were carried out on a vertical machining center. The simulation and experimental results indicate that a high accuracy stability can be achieved with error compensation, even when the moving state is changed. To visualize the effect of error compensation with naked eyes, a special machining process was designed for a rectangular workpiece. The machining results confirm that the proposed models provide a high accuracy stability and robustness. [ABSTRACT FROM AUTHOR]